Sorry, I can't think of any places off the top of my head for kits but when I'm looking I look in magazines and on the net. I build my own planes from plans. I get the plans from plan services like MAN {model Airplane News} AMA plans, RCM plans services {Remote Control Modeler} defunct magazine but the plans service is still in operation. When you buy the plans you get A copy of the building article, A very poor copy but the print is good, any photos suck!! Plans building is very easy, it's just like building A kit with really bad instructions. You have to figure out the wood needed, order it and then lay out and cut your own kit then build. A scroll saw and sander are about the only extra tools needed to do it. Have an extra set of plans made at Kinko's so you have one to cut from and one to build on. About it.
I took the plans from MAN for the 80 inch Sukhoi 29 designed for A 1.20 four stroke {very light plane} and I beefed it up then went with A 40cc gasser. You were looking for A good 1/4 scale 3-D kit??? Go take A peek!!!