I think coops are bit 'difficult' to maintain...get cheap or second hand shed..get fallen branch of from woods as a perch (about 2" across)...as for nest box..well even cardboad box will do for them with bit of bedding, and good thing is that when they have a rest from laying you can always burn the box and get new one..less mites and treatments..

The good thing about sheds are that you can get inside and keeping it clean is much less effort. You can build shelves to keep food bins on.
As for pen..well..hunt some timber and get some wire/ mesh panels..maybe some trips to recycling centres or tips would source some of that material for cheaper..or ask from your local builders if they would have something suitable that they no longer are able to use for health and safety reasons.