If you are not picky and not using a DVI monitor or willing to use a second monitor with vga you could just get one or two voodoo 2 cards. You keep modern support for current games but also leaves you glide support. Older games are scripted to request which display adapter they use so glide will run straight off the v2 or any other 3dfx card out there. There is 64bit driver support so people are keeping the drivers up to date. I am also a collector and current to what is going on in the 3dfx world. Recently been buying more
If you wanted to pare up lets say a gtx460 or a gtx670 with one or two voodoo 2 cards it will work with using a dvi to vga adapter then using the pass through cable if you wanted to keep to using one monitor. If you were willing to have an extra monitor just for glide use you won't need the pass through cable at all. Just hook it up to the card but there won't be a single or the screen will be black until a game was loaded. So in theory you can still use 3dfx voodoo 2 era cards on modern machines and still keep the latest cards for everyday gaming.
For Dos games the V3 on up is fantastic but highly suggest a dedicated rig due to speed issue and general compatibility such as having opl3 equipped isa sound card while running a pentium 1 era cpu. Can disable the L1 cache to emulate 486 level performance for certain games and disable the L2 to get 386 level performance for the really picky games.