Most prefabs are crap, I agree. And most of what you get online is too small.
I winded up getting ,similar to Aituvian, a rabbit hutch. It was about $150. Watch out for
Amazon delivery fees. Worked out perfect for a mama and babies, or some growing chicks for few weeks. Not for standard adult birds! I then surround whole thing with a dog panel (4-5ft ones on
Amazon, $50.) I used the plastic fence stakes (used for temp fencing) and zip ties and made an area. Of course this isn't permanent, but gave a safe, albeit little bit larger space. And got them out of the previous area they were in.
Although I went into that knowing that it wasn't super great and it's not their final permanent home. And I will need to modify and eventually paint it. Now these double as a med coup area / separation/ or for growing chicks.
One of the coops I have is the Producers Pride Defender Coop with run, at the time got it for $300 as a family was moving out of state. I do recommend ( if applicable) use barn or outdoor paint as well as lining the bottom with metal or linoleum. Also add extra vents for any or all coops.
Hoop coops are great depending on your area. Unable to in mine as the temps fluctuate so much.
For cheap route we did a 12 x 12 shed, wood floor with metal all around. At the time for supplies it was $1,200. You could always get a cheap metal shed at Lowe's for $400 and be better off space wise.
Try to scout Facebook marketplace too. I found an old playhouse that I am going to rehab into a breeding coop.
Unfortunately now, my 12 x 12 shed (5-6yrs old)and defender (7-8 possibly 9-10, as it was a year or 2 old when we got it) coops are starting to have problems so definitely doing coop refurbishing this year. Although they are quite old too. I definitely recommend trying to get something prefab, even if it's an old doghouse, crate, etc. Although if you have time, definitely make a decent one, but larger than you think. Also remember about storing supplies, feed ect (that goes for what you are currently feeding and what you have in storage. )
There's a variety of options, just see what works for you. You could always get something to tide you over until you source a larger one. I hope this helps.