i have a couple worked ones, both 1500+ retail. clear, unworked ones wont be less than 950-1k retail. if you can, its worth the money. the best balance of diffusion while keeping tatse.
the toros are great toobs. just a completely different experience. the toro(7/13 or circ/circ/, etc) will have a chunkier hit w/ a quicker clear. while most SG's are big on diffusion and dont clear as quickly, but provide more diffusion, therefore a 'smoother' or cleaner rip.
700 for 7/13 is just too much. keep lookin. shud be able to scoop a worked 7/13 for 600 or less.
obviously, i am a big SG fan. but if your budget is 700. get a worked stem/8. or get a clear stem/8 for 500. a great tube. and, are you sold on a double perc tube? singles are pretty tasty......