If you have spring compressors that will fit (like the type used on car coil springs) then it should be easy enough to do the rear shock yourself. Otherwise a place that does bike suspension will take 10 mins to swap it and probably won't charge you much either (cost me "a tenner for the tea kitty".)
Front springs are easy enough to do with basic tools, just takes time to take it all off. You want to take the forks off, take the caps off (best loosening them while still on the bike, just undo top triple clamp bolts first.) After the caps are off (wind the adjusters all the way out before you take them off), take the springs out, pour the old oil out (pump the forks to get as much as you can out), then hang them upside down over an oil pan and have a cuppa/beer. Then it's new springs in, fresh oil in and putting it all back together. Careful not to cross thread the fork caps, it's easily done and they are only soft aluminium.