I've also seen some shade tree methods to compressing the spring with clamps and such that can be gotten from Home Depot or somewhere like that.

Another option would be to check out AutoZone an auto parts store if you have one in you're area. They carry just about any tool for any automative repair that they loan out for free, all you do is leave a deposit that's refunded when you return it... I don't know if that only applies to paying customers that bought something... you'll have to call and find out.

Also check some Equipment Rental places .

It probably wouldn't cost that much though to take out your strut/spring assembly yourself and take it somehwere and have them swap out the springs... after all you've done most of the hard work, their just swapping the springs for you.