Buy 'em either new or used at your local music store. Daddy's Junky Music has piles of used turntables left over from failed bedroom DJ's dumping them for gas money. Most sell for about $100 USD. Plenty of consumer turntables can be found at your friendly record store for about 50 bucks.
You can also find used turntables online, at a flea market, or in your Nana's basement. I got one at Salvation Army for five bucks (not the one in the picture). I use it to clean my albums.
Here's a comparison of several models within a reasonable price range. These are not the battle-hard DJ warrior versions. If mere utterance of the word 'Skratch' produces sweat and bile, you'll most likely not need the DJ models, saving considerable money.
If you buy an older model (used), be sure you can replace the cartridge. Be aware that many turntables don't come with cartridges at all, you'll need to buy separately.
Cartridge design makes a far larger impact on the quality of recording than I had originally realized. Try Grado Prestige Black, the Sure M97xE, or the AT440ML. Prices can go higher than $1,200 for a cartridge. Wow. Too bad I shredded my teenage eardrums years ago at them 'Dead shows and Nugent concerts.
Make sure your follow your equipment's instructions for installing the cartridge and balancing the tonearm. Set up on a stable surface and you're good to go! Here's an excellent guide to turntable basics.
Hey, what are these wires supposed to go to...?