Gabriel is an aftermarket replacement like Monroe. Very inexpensive, I've seen them on Ebay for around $15 each. I have no experience with them, but I would never pay that much for them. You can get Honda OEM ones, plus a lot of upgraded aftermarket like Bilstein, Koni, etc for that (or close to it).

The spring compresser set I bought was $30 from Advanced auto. The fronts need a lot of compression (if stock springs), but the rears are pretty easy. Both are very doable DIY. You should do the rubber mounts and collar spacers too.

If this job isn't done yet, don't do it. Either do it yourself, or find someone that can help you. You'll get better parts AND save money if you do it yourself. With the extra money you could even get lowering springs and not have to compress them as much. Wether it improves your suspension feel is your own opinion, I don't like the lower springs. I did however like Bilstein HD's with stock springs.