mass production

Here we have mass production of the wee bird feeder i blipped previously.original blip of bird feeder.

these ones were built by my community access programme, and they have done a no bad job of them.
of course a thick coat of brown paint helps them look good! ;-)
This lot are going home with the students but i have more to be built and the next lot will be sold at a craft table sale within the college.
I dont know how much to ask for them though.
Any ideas what would be a good price for one of these?

p.s all monies are given to charity. (dont know wich as the dept usually rotates there charity of choice)