Have a look at this project, on freelancer.com.
The person posting it wants the functionality of the customer being able to choose a delivery date and a delivery time on a per-order basis. So, you can see 6 quotes, ranging from $250 to $800. All the buyer wants is what I have already coded and have in place on a few shops…as per here.
Funny enough the buyer also contacted me directly, and I quoted $100 in total – as it is two installs of existing codebases (one for the date, one for the time). Easy as 123, and not much time to actually so, hence the low quote. Had a reply asking me to reduce the price, then nothing else. I've emailed back and basically said "my price is good, so if you want it, pay it. If you don't want it, use one of the quotes on your freelancer project page".
My feeling is that if a shop owner needs code that they already see in place and working well, then why not buy it (especially if the price is lower than everyone elses!). Maybe I need to up my price? Don't know.