Alexis,
If you are concerned with losing money, if you find that 4x5 is not for you, then as well as buying at a relatively low cost, you might look for something you can re-sell with minimal loss (think of it as rent). Buying used with a well known make can help in that way. A number of people recommend Sinar as a make that is easily and cheaply available and can grow if you decide that you need more of 4x5. Using a standard make can also reduce some of the other issues like needing to mount lenses on obscure lensboards types. Sinar / Horseman, Linhof / Toyo / Wista, and certain standard sizes (4x4, 6x6) are common lensboard versions.
The camera can easily be the least expensive part, with lenses and film eating a large part of the budget. In that situation of stareting out, you are better looking into a complete kit from someone getting out or upgrading. If local they might even be able to take you out to show you how to use it.
Just some other things to consider.
Good luck and enjoy, as it changes the way you work and the way you see,
Len