Few tips.
go to the local arcade and ask if they have any old shelled out games to buy.
After I spend 400 bucks on mine (shipping to BFE where I live was most of it) I finally got a free cabinet from a friend of a friend who owns an arcade and he was going to give it to me for free... of course my wife wouldn't let me take it... sigh...
This should get you 2 joysticks of decent (but not great) condition and a few buttons.
If you have an arcade CRT that works (make sure first!) then go jpac. Otherwise, I would go TV
Then, look at ebay. Search under arcades
Collectibles:Coin-Op, Banks & Casino:Coin-Operated:Arcade
Then search for control panels, or joystick or joysticks (yes, they are different searches), and see whats around.
I got 100 buttons for about 10 cents each so I have plenty extras that have come in VERY handy.
Remember that joysticks go bad and aren't worth refurbishing in most cases... but a great start.
www.videoconnect.com seems to have the best prices, but a crappy website (mention it if you call). but 10 bucks for a happs joystick.
So what you should hope for.
Cabinet 25" or 19" CRT... free - 50 bucks
10 extra buttons (assuming cabinet has 2 joysticks with a few buttons each... you will probably want to add a few). + a few extra items to fill in an order to make it worth the shipping -------- $25
Jpac ($80 or so... haven't checked)
done.