Cor HF, I think that's a bit strong! We are trying to encourage people not scare them off.
I admit that there are a lot of poorly designed hen houses out there, but not all of us can afford bespoke houses either (not that I'm saying you can!) but all your "must haves" and "must not haves" in your list are virtually impossible to come across all at once. I think there has to be some level of compromise.
E.g. my main coop doesn't have a vertical sliding door - however if I wanted to replace it with an auto pophole arrangement it would be very easy to. It also has a metal dropping tray, but I've never had a problem with condensation... possibly because the tray is covered with an inch of bedding. But it does have a lockable nest box... so no sleeping in the nesting area.
It also has... shock horror... a felt roof - felt which has been properly bitumin-ed onto the wood (not stapled or sticky taped)
I think that there are quite a few new designs on the market now, which, while not perfect, are much better than they were a year ago. You certainly have a much wider choice available in the UK than you do in France!
For me the biggest plusses for a hen house are (not in any particular order except the first three!):
- Easy and large access to the inside - essential for cleaning
- Sturdy construction
- Shuttable nest boxes
- Sloping roosting bars
- Ventilation above head height
- No windows
There are lots of poorly designed houses out there mainly because they are machined wood construction made in Indonesia/ China as fill in jobs to keep furniture manufacturers plants busy during slack periods when they aren't making garden furniture. They are usually well made, fit together well and look reasonable quality. Where they fall down is the design in many cases is poorly adapted to chickens and they are made from flimsy materials which dont stand up to UK weather. You pay for what you get. If you just want a hobby for 5 years or so keeping patio or back garden chickens some may be a reasonable buy but if you want a robust house which will last 10 years plus and stand up to all weathers you'd better look elsewhere.
There's lots of well designed and built houses out there from the likes of Forshams, Smiths sectional buildings, Westaway Poultry and many other UK and local manufacturers. The advice is a little idealised if you want to buy off ebay I admit but it gives you the key pointers and you can decide to compromise on various things or even modify a basically sound shell. If the materials aren't spc'd ask the seller.
If you built your own it needen't cost a fortune Diggit had a well documented design thread on here which was a very good design and simple constuction and not too expensive. I think I included a link to it.
The secondhand market is also a possibility. I saw a used 4 year old Forsham Lenham 504 sold on ebay for £120 recently which I'd much prefer to many similarly priced flimsy houses. Also Eglus if you only want to keep a few hens or bantams or Cubes if you want upto 10 or so are very cost effective as Aunt Sally says though they aren't my personal choice but a good used one is a possibility.
Runs are very important and are often overlooked. Pretty much all low cost houses runs are inadequate. You need to budget almost as much for the run as the house unless you plan to allow them to free range the garden. You can look at the Domestic Fowl Trust housing for their aviary type runs with integral houses as a reasonable option or look at an electric net run which can be implemented for around £180 new.
HF