Your question is much like asking how big of a ball of string do you need to
reach between two cities? Answer: it depends on how far the cities are
apart!
In several serious software studies, the productivity of developers on a
team varied by as much as 100 to 1.
That means if your developer is good, you are getting 200 days worth of
work. If the developer is poor, then you are getting ripped off.
So, even if two developers charge $50 per hour, one developer could be 10
times as productive, and thus is really only costing your $5 per hour.
I am suspicious that what you ask for is only a two day job...but then
again, I have no idea what it is you are asking for.
I would say, you need to ask the developer is there any previous customers
that you can talk to, and even better go down and meet and see the actual
application running that the developer wrote (this is about the best thing
you can do to check if "other" people are happy with the developers
work..AND YOU go and see it run!).
If the developer is good, he will be happy to bring you to one of his
previous clients, and show the appellation running in the "real world". It
pays to shop around, and ask questions.
In the yellow pages, most fence builders for the same kind of fence will be
quite close in price (maybe a factor of 2 times different for the same job
at most). In software, the product is that of the human mind, and thus time
factors will vary by much larger numbers as the limits are not how fast you
can take fence posts out of the back of a truck (humans can only move so
fast)
Software on the other hand is a product with no physical attributes, and
thus the only limitations of software is the human mind. When it comes to
the human mind...things vary by a large amount..and your best bet is the
best talent you can afford.
I know many people who can play music. I know many people who can write
software. However, the Dixie chicks can easily fill a stadium based on their
talent, while the next person is stringing a guitar for change down the
street. The same difference applies to software...and you want to get the
best star for your money...
Talent makes a HUGE difference in software...but for putting up fences..you
don't have to worry as much compared to software.
Get the best talented developer with the best reputation you can afford..