Going on a date can be a difficult thing to organize, and when you are on a budget it becomes even more difficult. Here are some ways to get out of the house for a few hours for some "couple" time. This is geared a little more toward couples with kids, but the latter part will apply to everyone, and actually would be great for "girl's night out" events, too.
If you have kids, you will need a babysitter. If you have family in the area, that really helps make date night cheaper, because they will generally sit for free. If not, well, don't give up just yet. If you have friends that also have small kids, see if you can trade babysitting nights with them- they watch your kids, then you watch theirs to give them a night off. Otherwise, plan to spend about $10-$12 per hour for a sitter. You may be able to barter goods instead of money (for example, if you make fantastic pies or bread or some other consumable, or are very crafty, you could exchange a pie and some loaves of bread, or a handmade purse for babysitting for the evening). The cost of a babysitter is not being figured into the date for under $20, by the way.
Onto the date! Here are some ideas:
Movie Night: If you don't mind seeing movies a few weeks/m0nths after they first come out, check to see if you have a discount theater in your area. One within walking distance is ideal, especially in the summer, because then you aren't even paying for gas. For example, the discount theater in my area has movies for $3 per ticket or less (depending on the time of day), and the refreshments are even reasonably priced.
Coffee: Why not go out with your significant other and just spend some time talking, hanging out, and getting to know each other again? Starbucks is one option, but check around and see if there are any locally-owned coffee houses in your neighborhood. Some have live music, so sip your lattes and groove along! When my husband and I did this, we ate dinner first, then went out for coffee and dessert. Overall we spent under $15 for our date at a local cafe, complete with music by a local singer. A variation of this would be to go get ice cream and walk around somewhere while you talk.
Bowling: Yes, bowling! Bowling alleys are a fantastic, fun place to go for a date. There are always specials going on at the Brunswick Zone (a local bowling alley chain in CO), including games for $1. At that price, you could even afford some snacks!
Picnic dinner: Obviously, this would be best in the summer or in nice weather, but it is pretty easy, and inexpensive, to throw some sandwiches, fruit, salads, sodas and/or beers, etc together and go to a park. State parks require admission, but even if you end up spending $6 to drive your car in, that's still a pretty inexpensive date. Some parks don't allow alcohol, so you may want to check the policies of your destination before you head out.