Short version:
berkeleying AWESOME!, low cost $120 + $40 1 year membership for 10+ hours of kart time on weekend days (5+ hrs seat time given run groups, attendance, etc.) arrive & drive, fast karts, challenging track, great wheel-to-wheel, you get a t-shirt included in your price...
http://www.summitpointkart.com/index.php
Long version:
I just got back from a trip up to my buddies near DC for a weekend party and while we were there we decided to go over to Summit Point and run their "Kart Till you Puke." Basically it's an all-day-a-thon (we did Sunday 12am-9pm) arrive and drive which happened to coincided with their racing league. My buddies and I have all karted alot at Andretti in Atlanta which are 9HP Honda karts where the track is tight (indoor) and only reaches 35MPH tops. Some in our group have run at SP before in the karts as well. We've all AutoX'd and track-day'd.
We arrived at 1pm and ran a couple 11 min runs. However since it was a quiet day, with only 5 league racers running, 1 non-leaguer and then 5 of us in our group (3 of which had run the course many times) after checking our times they let us all play in the league since we were doing the KTP and were all experienced karters anyway to help up the grid and make it more fun. They have Sodikart RX7s with a top speed of 55mph, which are used by those arriving-driving, and to qualifiy for the league races, but then the league races run RX250s with a top speed of around 80MPH (none of these are shifter karts). Otherwise you have to run a certain time on the RX7s and pay another $40 to run the RX250s (outside the league).
We ran a time trial, then 3 jockey races in the RX7s switching karts and position to gain the best overall times as the top 6 of us 10 got to run the league on the RX250s without paying the upgrade. The best part was those top 6 could continue to run the RX250s after the 3 league races were run without paying the upgrade fee for the rest of the day, plus the overall RX250 winner of the combined 3 races won a free RX250 KTP ($200). Yeah, it was pretty cool. I managed to qual 5th out of the top 6 for the RX250s and managed to hold there throughout the 3 RX250 races, but me and #6 who were complete noobs to something so fast and powerful as the RX250s had a sweet battle going the entire time. The other 4 guys were experienced racers and we couldn't match them but my times were steadily improving by the end.
In the end, the event cost me $160, I got a t-shirt, ran 7 races on the RX7s and 3 races on the RX250s, that's 111 minutes of racing for $160, and we bailed at 6pm (there was 3 more hours of racing) as we were physically exhausted and sore. Had we kept racing we were confident we could have run 5-6 more times given how few people were left but our bodies weren't in shape to handle that level of abuse.
$/fun/time invested/effort meter is pegged into the red on this one guys, I am seriously impressed by the karting at Summit Point and it's a good thing I don't live closer...