Is a beam expander worth the money?

I'm thinking of buying a Jetlaser PL-E Pro in 300 mW. The 10X beam expander is an additional $90. Is it worth it? Also, what does it do that the focusable part of the laser not do?

Basically, a focusing lens rapidly brings the width of the beam diameter to a very small dot but then the beam flares wide right after that point like a hourglass or an "X"
Normally a lasers beam gets wider as you get further away from the front of the laser = divergence.
A beam expander does the opposite, it makes the beam wide but then as you get further away from the front of the lens the beam generally gets narrower.