Keep Your Side Project Under a Coffee a Day

Set a daily limit before choosing a model

Start with a number that feels ordinary enough to sustain. For many developers and students, the cost of one coffee a day is a useful ceiling because it turns an open-ended expense into a familiar habit. You might translate that into a monthly limit of about 90 dollars, then lower it if your project is still experimental.

Use the monthly figure as a boundary, not as a target. A side project should remain affordable even when a week becomes busy, a prompt needs several revisions, or a debugging session takes longer than expected. Write down the maximum amount you are willing to spend and decide that you will pause work when the limit is reached.

Separate exploration from routine development

Next, divide your AI usage into two broad activities. Exploration includes architecture questions, unfamiliar research, large code reviews, and difficult debugging. Routine development includes short edits, test explanations, naming suggestions, and small documentation tasks. This distinction makes model selection much easier.

Use a stronger model only when the task benefits from deeper reasoning or broader context. For short, well-defined requests, a faster and less expensive option is usually enough. Gemini 2.5 Flash can be a practical choice for routine questions and quick iterations, while Claude Sonnet 5.5 may be reserved for the parts of a project where careful reasoning saves meaningful time.

Give every tool one visible spending boundary

A shared, untracked collection of API keys makes costs difficult to understand. MyRelay gives one person one key and one budget, which is a useful arrangement for a personal project. It lets your command-line tools and OpenAI-compatible applications draw from the same spending boundary instead of creating several independent billing paths.

When the setup matches your needs, create an account and set the budget before connecting your development tools. Treat that budget as a permission limit. Do not increase it simply because a request was rejected or because a model produced an incomplete answer. First find out whether the issue came from the prompt, the selected model, or the application.

Measure tokens before changing your habits

After a few sessions, inspect the request history rather than guessing where the money went. MyRelay members can see the tokens and cost for every request. That detail helps you identify expensive patterns that are easy to miss, such as repeatedly sending an entire repository, including long logs in every prompt, or asking for a complete rewrite when a focused patch would be enough.

Look for the requests that consume the most input tokens and ask why they were large. Remove duplicated instructions, trim old conversation context, and provide only the files or excerpts needed for the current question. Small reductions repeated across dozens of requests can matter more than one dramatic change in model choice.

Build a low-cost request routine

Make each request easier to answer on the first attempt. State the desired result, include the relevant context, and describe constraints such as the language, framework, or expected behavior. Ask for a focused response when you need a focused response. This reduces the number of follow-up prompts and keeps the conversation from accumulating irrelevant history.

• Begin with a short question when the task is simple.
• Attach only the relevant code or error output.
• Ask for a diagnosis before requesting a broad rewrite.
• Start a fresh conversation when the existing context is no longer useful.
• Review generated changes yourself before asking for another revision.

Review the budget on a fixed weekly schedule

Choose one day each week to check total usage, average request cost, and the tasks that consumed the most tokens. A regular review is better than checking only after receiving an unexpected bill. If spending is rising, reduce context size, move routine work to a lighter model, or temporarily limit open-ended experiments.

You can also make the budget work harder by sharing a referral with friends who are already building projects. MyRelay members earn 10 percent when invited friends pay. That should be treated as a small offset rather than a reason to increase usage. The main goal is simple: keep the project useful, measurable, and comfortably below the cost of a coffee each day.