Nah, the 'filters' can be had for next to nothing, I picked up a 49mm Hoya +3 at a camera swapmeet/market a couple of years back for $5. Works well.
Might be worth checking Photographic Trader magazine.
Edit: Oh and there's a ring adaptor available that allows you to screw a 50mm lens onto the front of another lens, front to front, so the rear element of the 50mm becomes the front element.
This works really well but can have limited FOV, and the subject needs to be very close to the 'front' element(where the film plane
would be normally) which can make lighting difficult.
This even works well with point and shoot cams, but the FOV is even worse and the zoom needs to be used.
If you just need to do a couple of quick shots, do as I do, forget the ring and hold the front of the 50mm up to a zoom lens
