We've never been to any Bethesda Volleyball Club activity, so I cannot provide any valuable insight on how they run their clinics or how good they are. If the clinics sound pricy, it's because they are. Volleyball clubs milk the parents in this area as much as they can. Just do the math: renting space in an MCPS facility costs $17 / hour. If you charge $35 / participant for a 2-hour clinic, the first kid pays for the space. You can pay the coach very generously and you still make a lot of money, especially when you attract a large group.
The other option you have is to go the rec route, which is more reasonably priced. I suggested a couple of alternatives on a different thread (and used copy / paste below). The disadvantage of the rec route is that coaches can be hit or miss. They could be ok for one or two seasons to figure out whether your kid likes the sport. If you decide to pursue the sport at the next level, make the decision as soon as possible to avoid forming too many bad habits (which will take a while to correct). The sooner you start playing club, the higher the chances that your kid will be successful in school sports.
City of Rockville has a volleyball activity for middle schoolers that starts in a few days (and they seem to have some spots left). To register, go to the following link:
https://secure.rec1.com/MD/city-of-rockville-md/catalog
and search "Volleyball" in the search box. That should be a good intro to volleyball.
Alternatively, you can join the Gaithersburg league (but you would have to register on the waitlist and hope that a spot will open):
grade 4-5:
https://anc.apm.activecommunities.com/gaither.../search/detail/14218
grade 6-8:
https://anc.apm.activecommunities.com/gaither.../search/detail/14220