Seems like I used to see SFC1gold for about th 10-15 dollar range around here. (a couple of weeks ago I saw SFC3 for almost 15 bucks, ouch)
I think checkin' the internet is probably the best bet now, since it's way out of stock most places. Outpost.com has an SFC1/Starfleet academy combo (jewel cases only) for 9.95, so the game is still out there and can be had with some good deals. I think it was also available in a combo pack with several other games at one point, so shopping around might nab you some extra goodies if they are your cup of tea, and depending on how much of the original material you want.