If your LBS is a good one, you might start there. They may have access to an inexpensive fork which would work on your bike, and if they know their stuff, will know what works. They may also have switched out a rigid 29, or an inexpensive 29 susp fork with lockout, for a better susp fork on a customers bike, and maybe they could put you into contact with that customer. But I'd start by knowing what specs I need to look for, and if a good LBS, could help with that.