Wow.. but I use the Canon Rebel XSi/450D(in those homecoming pictures, i used the nifty fifty) so I think it's ok to use an entry level dslr/cheap lens as long as you're able to deliver!
now to see if anyone would still want a photoshoot for $20 after my homecoming shoot being so cheap... heh heh heh
Thank you so much for your input! =D
I liked the 2 photos you linked. I'm definitely not in the wedding/couple/prom/high school photo world, but I think it's good work. Good exposure on the subjects, in focus, and nice that the background is slightly underexposed.
I'm agreeing with rafaelsynths, you've proven you can take some really nice photos, time to charge a bit more. $20-$30 is definitely not out of range for most kids going to prom, even if their parents won't help out with it. Seriously, that cost is lost in what most girls spend on dress, hair, makeup, etc. If you do more than 10-20 minutes & deliver more than a couple of photos, I'd think about charging more too. Especially if you have a ton of bookings. Supply and demand! If you're supply of time is filled up by demand, charge a bit more.
In terms of equipment, you're doing just fine. I had the 450D/XSi as my first dSLR, and loved it. Was silly enough to have the nifty-fifty, but not really use it. Now, I've learned to really appreciate primes even though I've upgraded my body =D If you're going to be doing some group shots with more than 2-4 people, I'd look at renting a wider lens though, since you'll start having to back way up. If you have a local camera shop that can rent, I'd recommend seeing if you can get the 24mmL or 35mmL. Those will give you ~38mm & ~56mm lengths, while the 50mm you have now gives you ~80mm for reference. If they want you to plunk down the full replacement cost on a CC (lots of places want this, ugh), check with your parents, or rent through an online place like LensRentals.com (I've rented from here, you need a CC, maybe you can work it out with your parents?).
Hope some of this is useful, and keep shooting!