All the above suggestions will get you there - it's just not rocket science. You can make screens up yourself, but take it from personal experience doing more than 1 or 2 and trying to get them flat will probably convince you otherwise. However, if you'd like an easy solution, I would offer you the setup I made before I designed my darkroom, below cost. It consists of 24 X 30 inch Calumet Zone VI Drying Screens and a wheeled, movable ClosetMaid enameled metal rack. The rack is made up of 2 separate drawer racks ordered from Home Depot and combined in such away to fit the 30 inch width of the screens. This "ladder" structure holds 11 screens total. The whole thing is light enough (a few lbs.) to be moved either by rolling or picking it up to any location you wish. My darkroom needs were satisfied before I ever used the setup. No part of it was ever used and the screens (3 boxes of 4 screens - 12 total) are still in their original boxes. The screens, though not cheap, are on a par with what regular pre-made fiberglass window screens (which the Zone VI actually are) of that size would cost. I will offer you the 3 boxes of screens at cost ($44 X 3 = $132) and throw the rack in for free (it was around $50) - you pay shipping.
PM or email firstname.lastname@example.org , if interested - Ben