If you type !c4 in chat or sm_c4 in the console it will give you (if you are on T side) a C4 bomb.
I am currently using it on my server and it is working great.
Feel free to leave suggestions or comments. Everything is welcome.

Cvars:
sm_c4_points (Def 250). This controls how many points are needed before buying a C4 is possible.
Commands:
sm_c4 or "!c4". This gives a bomb at a set amount of points.
Plugin / Source