I myself am a freshman so i know low budget. Umm in your case if you really want to improve on what you have I'd bite the bullet and save up to around $300, b/c right now if you (and I'm not saying you will be) go ahead with your $200 budget for both the amp and the sub (I assume your like me and crave ground shaking, stomach wrenching bass
)then you might be dissapointed, but if you tough it out like i have to do alot then you'll be much more satisfied b/c then that'll give you around an extra $50-$75 for the driver itself cause you have to keep in mind shipping and the cost of the material for you enclosure, I was looking at getting the same 300 watt Bash amp and its hard to find them for under $200 so if I'm getting you right your spending 150 on the amp since you wanted a sub for under $50 on a $200 budget so if you found the Bash amp for around $150 i suggest you go ahead and get it then just wait it out till you can get a little more wiggle room on your driver selection.