You can spend a LOT of cash on a cartridge, that's one reason I've always viewed the V-15 as a kind of cartridge equivalent to the SM57/58, i.e. there are better cartridges but few that offer the same ratio of price to performance.
The s-shape arm on your SL1200/10 is made non-exclusively for Technics at a price of approx $10USD. This company:
http://www.systemsbyshorty.com/index.htm
can provide you with an armboard conversion so that you can fit any arm with a REGA type mount to your SL. Even the basic RB250 (rrp £125 GBP) provides an enormous improvement over the standard arm, the mid-clarity and extra bass-punch will grab you immediately.