I can tell you from experience that Jeremy and his company do an excellent job. I was extremely pleased with the work he had done for me on my 00 YZ426. I was like you...just getting back into the sport... and I had been riding a worn out 92 KX250 with a very soft suspension.
I would have to agree that Terry's estimate is correct. Maybe less, maybe more but if you are going to have it done then you have to go with MX-Tech. Quick, professional and courteous. I never had any problems either.
I kept the bike this way for about a year and a half. Then I felt a lot more secure on the bike and decided to switch back to the normal height. For that, I consulted Jeremy again because he was obviously the guy with the needed info.
Jeremy could also fill you in on your options, maybe there is another way to achieve what you are wanting.
Good luck.