I know it depends on how bad the stretch marks are,Like losing an excessive amount of weight then a tummy tuck will be the only possible solution,I started lifting a couple of years ago when I was young 17,I knew nothing about stretch marks except most women get them during pregnancy,So I saved up for a few months,Saw an ad for a MultiGym,I got it for £300 when it should have been around 700 at the time.After a few months I got them on the Inside of Both Arms & Inside Both Thighs.So it really messed me up, I contacted a few places only to be told there was nothing that could be done about them.So I slowly resigned myself to the fact that there was nothing I could do,2 Years went by & I started seeing a girl who worked in a Beauty Salon,So when I was in tp pick her up one night,She was with someone,I was having a browse of their possible treatments & noticed a poster of a new treatment they were offering called Futur-Tec, So I booked a course of 10 treatments(got it for half price),started 2 treatments per week(Mon,Fri),Almost 6 months later all the marks had disappeared by around 60%,We split up shortly after,So I wasn't getting anymore deals from them,I contacted the company to see if they had any reconditioned machines,only to be told they only sell brand new machines (£7500) which I couldn't afford,So I saved up for around 8 months & bought my self a microdermabrasion machine,Started working on myself & while they haven't gone away 100% they are pretty close.So If you can afford it find a beauty salon that offers futur-tec or even microdermabrasion & stick with it for as much as you can afford & you will get results.
For more info on Futur-Tec
http://www.caci-international.co.uk/index_frames.html
When I can afford it I will definitley by myself one of them,Although surely they must have some re-conditioned machines for sale(People that couldn't afford to keep their payment plans up or salons who have gone out of business or whatever,I even have checked ebay for the last year or so & haven't come across any for sale).