It can be pretty comical (and impressive) to see what kind of clothes you can get at a thrift store for $5. Pick out outfits for each other (or for yourself) using no more than a pre-set budget ($5 is plenty), then wear the outfits to do one of the other date ideas (bowling, ice skating, etc)
If you know someone who likes guns, you can easily convince them to take you shooting. There are usually indoor shooting ranges if you live in a place where you don’t have an outdoor range nearby. You can take it one step farther and do some sort of “gun safety” class before shooting as part of the date.
This is another big hobby for a lot of people. Flying a model rocket can be done for under $20 (but obviously, some people get much more elaborate). If you are lucky enough to find an event, you can see hundreds of these of varying complexity. But if not, it’s still fun to pick up a starter kit at a hobby shop and build one together then fly it a few times.
There’s a lot more in hot air ballooning than you would think (they’re harder to fly than an airplane) so it’s hard to get someone to take you up. But if you’re lucky, this can be a really fun adventure. If not, they have hot air balloon events where you can watch dozens of them take off at once.
There are lots of cool things to be seen if you’re a tourist outside of your state/country. In Arizona we like to go to Mexico because it’s not too far away and it’s quite a cultural experience.
Again, a date that’s probably more for the guy than the girl. You can buy all of the parts you need to build a potato gun for less than 20 bucks (ammunition included!) which is a couple of PVC pipes and an ignition source (like a lantern lighter and hairspray). Good fun — a decent potato gun will go 50 yards. You can find instructions all over the internet.
Now that you’re older, you can probably engineer a really cool treehouse or fort. Wood isn’t TOO expensive, and if you already have the tools, you can make a pretty sweet club house either in your back yard or even out in the woods somewhere.
Most people don’t think of this as a date, but it’s great for a group. If you know someone with a boat, you can go water skiing, tubing, wakeboarding, knee boarding, etc. etc. at a nearby lake.
Camping is a blast with friends. Be sure you’ve got all the gear you need, and bring along card games, board games, snacks and lots of wood for building a giant bonfire. If you don’t want to camp overnight, grab a campsite (or if you’re in arizona, the desert works fine!) and build a giant fire for a few hours.
If you don’t know someone with horses, this can be difficult. You can choose how long you go for and where to. You can also decide whether to ride together or to split up. Great opportunity!