Let me just add an Amen to DaveG's post above, and also clarify: I DO sell SOME of the pieces/parts you need to build a Y-Wing, but most specifically and importantly do not sell any of DaveG's armature files, do not sell the head piece, and won't sell you anything you can get directly from Plastruct or a hardware store. I sell sets of several hundred greeblies, with which to dress up the Y-Wing
once you have already built the core and armature, and while I sell roughly 97% of the greeblies you do need, there are still a dozen or so that I don't sell simply because a.) somebody else makes them better, b.) I'm not good enough at two-part molds, or c.) I haven't found the original source kit from which to make a casting.
So this is simply to say: the current state of building your own Y-Wing is that you need to go to several different sources to get all the pieces you need, and these include but are not limited to:
DaveG
Masterpiece Models (for Greeblie Packs, Y-Engine Greeblie Packs, and Complete Recastings of the Aurora Sealab III)
Myself (greeblies and T-plate only, this parts run is still open)
Falcon 3D Parts
Ebay (for L'eggs Pantyhose, for Airfix 1/144 Saturn V (x2) that predate 1994, and any other original donor kit you must have)
Plastruct (for
T-bar struts item #T-8, most notably)
Shapeways (Esp. 308Bits, Falcon3DParts, BowmanArt, and Goldberg Arts)
Your Hobby Shop (esp. if they sell consignment old models)
Your Hardware Store
Hobby Lobby
Etsy (for Jason Eaton decals, etc)
Your local model club, model convention, model show, model swap meet, etc.
Your studio scale model buidling friends, either real or virtual, who have already built one, and may have a tip, a casting, a spare part, a clue
Lots of time, money, and most importantly: lots and lots of patience.
Long story short: lots of us on RPF are eager and willing to help. But we do appreciate not being approached as though we are a one-stop shop for a ready-made kit. The guys who DO offer those "complete" kits (aka "garage kits") are amazing, but even they have a hard time keeping up with demand, and their runs are usually very limited, even though sometimes you can get lucky on Ebay and find someone selling one who bought it years ago but now realizes he doesn't have time/patience/skill enough to build it.