I got mail from somebody with a vision for an app, wanting to know how much it would cost to build their idea.

This is my advice to him, with a few specifics redacted:

Hey, (Name).

I only have an approximate answer, but I’ll try. First off: 800-1000 hours at $55/hr isn’t an unreasonable estimate at all for a mid-sized app. There are people who can get this done in a lot less than 800 hours… And they’ll all charge more than $55/hr. So you’re unlikely to get it done well and much cheaper than that. You could get it done badly, usually overseas, for much cheaper than that, but there are a lot of obvious pitfalls – it could work, but it often doesn’t.

You have a full, rich site idea – you have a lot of ideas for “extra” features like categorizing shared (data). You haven’t trimmed your idea down to its leanest form. The very best developers will work with you to refine the vision you have for the site and figure out what’s important to your users. As a side effect, they may be able to do it faster be removing parts that aren’t necessarily vital, such as the categorization… Or put off features that are good, but aren’t 100% necessary at launch (following other people’s shares?). Or find a way to use an existing network and base the friend/follow feature off that (Twitter account? Facebook?).

Some part of what you’re trying to do is its “most unique” part, something that makes it different from other sites. Otherwise why would you spend thousands of dollars to build it? In that way, a really good developer can “tease out” that vision and build just the smallest thing that tests it. And they can do that in a lot less than 800-1000 hours. Then you can build only the later features that makes sense. Or if your initial idea didn’t work, you can refine that instead of building “extra” features that will only matter when and if your first idea is really working.

But $55/hr would be very, very cheap for a really good developer, Rails or not. You can get a Rails dev for $55/hr, and they will eventually be able to do the things you list there on the features. Usually you should expect to pay more for a CA Rails developer, though, more like $75/hr.

But the best thing you can do is to refine your vision down to something smaller – Startup guys call it an MVP (“minimum viable product”). Because it’s much cheaper to test your ideas with an MVP than with a full built-out site… And until you have something fun that feels good, building a bigger site just burns your money and slows you down.

The other thing you should consider for a (data)-sharing site is design. How pretty do you need this to be? How good does it need to “feel” to users? Do you need nice visual transitions? If you’re going to need a designer, do NOT have a dev build the site and then try to “paint” on the design afterward. The designer will have strong ideas about how to do things and you can get the most value from a good (and expensive!) designer by asking before you have the whole site decided.

Also, a designer may produce nice mockups that will show your developer exactly what to build. Communicating exactly what you want to a developer is very hard – the feature list above could be any of hundreds of different site layouts. Single-page? One big Twitter-style feed? Separate SoundCloud-like sub-pages? A developer could do exactly what you said there and still disappoint you, or just produce something ugly and unusable.

If you’re going to need a designer, figure that out early. If you aren’t, make sure your developer has good work in their portfolio that they have designed. Also, expect to pay more.