The qwestions are: can you animate? And much much longer are you willing to wait until you release your games?
Animation takes way longer to learn, that modeling, and texturing.
If you think you're ready to start making good animations (animations that YOU like, not us), then go ahead, buy weapon creator, or of course, if you think you want to wait some long months or perhaps a year.
If you think you still don't like your animations and want to release a 'quick' game, then buy MP5.
In my case, i buyed both, i specially buyed MP5 to help me up learning more weapon animations (this way i don't have to be looking at 2 games at the same time to take tips on how the weapons fire/bullet loose animations, etc.), also, it showed some support so he continues making more models (when i release my model pack, wich is almost near completetion, i'd also like to people to buy it
).
My love is seperated in 2 parts, 1 of them is 3ds Max 7, the other; FPSC.