It's not on-topic on Stack Overflow for all the reasons Padded Cell mentioned, and those reasons mostly apply to Programmers as well. But we have an additional clause in our FAQ that applies to these types of questions:
What about other programming related questions?
Please note that the following subjects are considered off-topic here:
- What salary/wage should I ask for/expect? (Too localized to your place and time)
The reason for this is both Stack Overflow and Programmers want questions that apply to programmers in general, not just very specific situations that'll only be applicable to yourself. That is, the blue part of this diagram:
It's incredibly difficult to make a question about compensation or pricing applicable to a general audience: something that costs $5,000 in New York City would be dramatically different in Tulsa, Oklahoma or Jakarta, Indonesia. Or heck, even 100 miles away.
Outside of geography, it depends on current market forces, the quality of the work, the talent of the developers, etc. But even beyond that it depends on how well a negotiator you are. Two people with the exact same set of requirements and qualities can come up with a vastly different price because of this.
However, estimation questions are on-topic on Programmers as long as they aren't about asking for cost estimates. Think questions like:
- What factors should I consider when estimating X project?
- Should I take into account X aspect of the project when estimating?
But most, if not all, of the general questions about estimation have been asked already. If you are interesting it learning how to fish instead of surveying people's opinions about what specific projects should cost, I'd start by doing your homework and reading the questions in the estimation tag.