Jeanette and rogueish have good advice. When I got back into home processing after a l-o-n-g layoff, I bought a Beseler C76 used and It did everything I needed until I got the Speed Graphic. Truly the lens system is the most important thing to consider with the light source next. A 5x4 enlarger might be a little clumsy in a bathroom-darkroom so a 7x6 might be better.
Be advised: you may become addicted and suddenly desire to move up to medium or large format as soon as your work is displayed and sold(?) et c. If you stick with a 7x6 or larger enlarger, you can easily deal with this malady by adjusting your lens inventory.