I reckon when I did my DAS course (four years back), it cost a total of about £3000 all in, breaking down to
Course plus test resit - £650(ish)
Helmet/textile clothing/boots/gloves - £300 (Helmet £100, textiles £100, boots £60, gloves £40. Try J&S in Hamilton, they do cracking deals)
Bike (Suzuki rf600) - £1500 (The sv650 you said you liked can be had for £2000, the slightly more rounded frame older model goes for as little as £900 now. good first big bike too!)
Insurance - £450 ( shop around, but the first year's a killer. No claims for a car don't count.)
But that's the lot, from not ever having had a bike at all to Being competent to take a 600 out on the road, and properly dressed for it. The insurance drops each year in a way car insurance hasn't, too. If i'd still had the rf600 it would have been £145 this year. The rf900 streetfighter I use now was £195.
It's well worth doin!
G