Blog 23 September 2026

Cheaper AI models this week: what Class 12 and college students should actually use

Cheaper AI models this week matter if you already use ChatGPT, Claude, or a coding assistant for notes, code, or intern work. On 22 September 2026, two labs cut prices on the same afternoon. Anthropic released Claude Opus 5.5. OpenAI released GPT-6 Sol and GPT-6 Luna. This page is a student price-and-use check, not a product review.

If the words below feel new, read this first. An AI model is the software that answers you. You type a prompt. The model replies. Labs charge money when you use their API (the paid pipe that apps and scripts talk to). They count usage in tokens. Think of a token as a small piece of a word. About 750 English words is roughly 1,000 tokens. Input tokens are what you send. Output tokens are what the model writes back. Output is usually costlier.

What changed on 22 September 2026

Anthropic said Claude Opus 5.5 is built for long coding and knowledge work. List price is $4 per million input tokens and $20 per million output tokens. That is 20% below Opus 5 ($5 / $25). The company also said typical workloads can cost about 40% less than Opus 5 because cache reads fell to $0.20 per million tokens and the model writes faster. Official note: anthropic.com/news/claude-opus-5-5.

OpenAI said GPT-6 Sol and GPT-6 Luna sit under the flagship GPT-6 Astra. Sol is the mid-heavy model for coding and harder work: $2 input / $10 output per million tokens. Luna is the small, high-volume model: $0.10 / $0.50. That is about half of the GPT-5.6 promotional prices OpenAI compared against. Sol and Luna rolled into ChatGPT Work and Codex for Plus, Pro, Business, Enterprise and Edu. Free and Go users get Luna on desktop, as reported in the company note covered by Reuters.

These dollar prices are list rates in the US API. Your college Wi-Fi chat box may look “free” because the institute or the app is paying. The bill still exists somewhere. If you are burning API keys on a personal project, the bill is yours.

Which model should a student pick this week

Class notes, MCQ drill, short summaries: start with the cheapest chat you already have. Luna-class or a free campus login is enough. Do not open Opus 5.5 for a 10-line summary.
Coding assignment or intern ticket: Sol or Claude Opus 5.5. Sol is cheaper per token. Opus 5.5 is the one Anthropic is pushing for long agent coding. Test both on one small function before you switch a whole repo.
Long research reading with citations you must check: a mid or high model. Then open the original paper or .gov.in / institute PDF yourself. Models still invent page numbers.
Who should skip paid API this week: anyone whose college already blocks these tools in exams, anyone paying in rupees on a card they cannot explain at home, and anyone who only needs grammar fixes. Free tiers cover that.

A simple rupee picture, not a promise. One million output tokens at $20 is about Rs 1,700 at a mid-September dollar rate near 85. One million at $10 is about Rs 850. One million at $0.50 is about Rs 43. Most homework chats use far fewer tokens. A 2,000-word answer is not a million tokens. A weekend of sloppy agent loops on a full codebase can be.

Campus rules still beat the price cut

IIT Bombay and other campuses have already treated exam-time AI as a discipline problem, not a tech demo. Read the house notice before you paste a question paper into any new model. If the course says “no generative AI”, a cheaper model is still a violation. If the course allows AI with disclosure, write the model name and date on the first page. “I used Claude Opus 5.5 on 23 Sep 2026 to outline section 2” is enough. Do not hide the tool and then argue you only used it for grammar.

For the exam side of this, see our earlier note: IIT Bombay exam AI case: what campus students should do.

What to do in the next seven days

1. Open the official pages, not a WhatsApp forward. Anthropic: the Opus 5.5 news post. OpenAI: the GPT-6 Sol / Luna developer note. Prices move. Screenshots from Tuesday can be stale by next week.

2. If you pay for API keys, write three lines in a notebook: model name, date, last month’s spend. If you cannot name the spend, turn the key off.

3. For a live project, run the same 20-line task on the cheap model and the mid model. Keep the cheaper one if the diff is clean and tests pass. Keep the mid one only if the cheap one fails tests twice.

4. If you sit placements in software or product, add one line to your project README: which model, which date, what you checked by hand. Interviewers now ask this. “I used AI” is not an answer. “I used GPT-6 Sol, then wrote the tests myself” is an answer.

5. Skip the AI-welfare and “pain button” lab stories for this week’s action list. They are research demos. They do not change your assignment deadline.

Who this page is not for

This is not buying advice for a coaching package. We are not ranking Claude against ChatGPT as a brand fight. We are not saying a price cut will raise your CTC. Indian IT stocks still fell on 22 September even as US chip names rallied. Your placement sheet and the API invoice are different files.

Also skip this page if you have not yet read your own institute AI policy. The policy wins. If there is no policy, ask the course instructor in writing and keep the reply.

Numbers above follow the 22 September 2026 company notes and the Reuters / TechCrunch write-ups of those notes. If Anthropic or OpenAI change the rate card, their site wins over this page.