mmm I dont know of a husky 75 .. and also the husq 901 was discontinued in 2008 and the S15 replaced it. The husqy range now goes. 901/S15, 905, 910, 936. S15 is £269 RRP the Pfaff hobbylock 2 is £265 RRP. If he has a 901 from the shop.. ex demo or something that might be a bargain, if he still has one.
Really the rule is, spend what you can afford to spend on it. if you can afford the next model up, go for it. If its not going to pay for its self don't bother
looking at parts for those machines, pfaff is cheaper btw.