I don't have a wine cellar. I am betting you don't either. But, that has not stopped me from buying and collecting wine and it should not stop you either.
The first thing to know is that the enemies of wine are heat, cold, light and dramatic temperature changes. So, if you are storing your wine in a cabinet above the stove, STOP READING right now and go move it!
The easiest, cheapest way to store wine is in a box in a closet. But not in any old box and not in any old closet. Ideally, your box will be a Styrofoam shipping box. These boxes are great. The Styrofoam acts as an insulator and helps regulate the temperature of the wine. Gives it some cushion too. You can buy these boxes at wine and liquor stores. If you have ever had wine shipped to you, it likely came in one of these boxes - so save them. Your closet should be located in a place that does not have too many temperature fluctuations. That is probably a closet that does not have any contact with the outside walls of the house.
A bit less easy and cheap would be to look into off-site storage. You can get a relatively small cabinet (maybe 12 cases or so) for not a lot of money. Check around for pricing in your area. The pros are, you know your wine is being kept at the right temperature. The cons are, you need to plan to get your wine out before a dinner party.
You may want to use a combination of the above two methods -- wine in boxes in a closet for drink-now and less special wines, and off-site storage for wines that you want to age or are more special.
A dedicated wine refrigerator would be your next step. You can get them in many sizes and at many price points. We actually have three: a small fridge from Costco in our pantry that holds mainly whites and drink-now wines, and two Vinotheque wine fridges that hold quite a bit of wine. The Vinotheque wine fridges are available in many different configurations and finishes.
Have fun buying, storing and drinking your wine!