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how much are they and what are they called?

UVA are usually household lights, and are used for heat. Most bulbs that give off a UVB light will not give off the amount of heat you'll need/want. A good light that does give off both is the ReptiSun 10.0, it puts out 10% UVB and 30%UVA, do the pricematch at Petsmart and you can get it for 25$

how long does that bulb last?

I hear it needs to be replaced once a year, this of course is due to the diminishing UVB output.

A mercury vapor bulb (MVB) will provide light, heat, UVA and UVB. It's an all purpose bulb. They're pricy - I think I paid $45 or $50 for mine. The UVB they put out is more intense than what you get with a flourescent bulb.

Here's a link with some products:

http://lllreptile.com/store/catalog/rep ... por-bulbs/

The Powersun and T-Rex bulbs are MVB's. The kind you'd use for an aquarium are the flood lights, not the spot lights. The spot lights are just much too strong.

There are special considerations with MVBs because they are so hot and intense.
1. They are not suitable for aquariums under 55 gallons.
2. You need to use a ceramic light fixture.
3. And, the distance between the light and the basking spot is very important because if you get the bulb too close you'll overheat or burn the turtle.

If you've got these considerations covered, then I think they are great because they put out stronger UVB and they are all-in-one.