I have also converted a shed, but mine was already in place. It might be a little out of your way to visit, but I'd be happy to take pics of anything you want to see, and offer what conversion help I can. The hardest part of mine was building the outdoor run, which you have to do in any case. Converting the shed was just a matter of adding ventilation and a pop door, and some kind of roost. Easy cheesy.
If it were me, I'd go ahead and plan out the scratch build, so that I had a good estimate of cost. Then I'd shop out used sheds, and see if I could get one for less. I haven't gone all the way through this process myself, but my instinct is that a used shed will be significantly less money than the materials to build one out - by half or more. LPT bought hers for 100 bucks, and I'm absolutely positive you can't build one for that. I've seen hers, and to scratch build it would be more like 300, or more.
I would love to see pictures. We plan to go see LPT's next week, she is really close, and then we also want to go up and see Chickcrazed's cause she is not too far either. So I am thinking after I see their's I will have more questions and that would be a good time to see some pics of yours. I am a little jealous of LPT's $100 shed - I'd even be excited about a $200 shed, everything I am seeing on Craiglist is several hundred dollars or more (although hubbie is a great negotiator) and then add having to pay someone to transport - hey just realized that we have a trailer hitch on our van, I looked at Uhaul and trailers are not terribly expensive - not sure why I did not think of this earlier!! Duh!
We have a dog run - we need to get finer wire around it (right now it is lined with pallets for daytime play!) and figure out exactly how we will work it with the shed, but my husband can easily figure that out. It would be great if next week we were able to get a good deal on a shed and just be able to skip the small interim playhouse coop altogether. As long as we can get it well ventilated before we go on vacation (when neighbors are taking care of them) we can worry about other modifications after our vacation. So we just need someone to list a decent shed (next week after payday) and we need to see it first before it is snatched up. All the stars must align perfectly! No problem right!