The truth of the matter is that nothing will protect your house's wiring, appliances, etc if lightning hits it directly. However, panel surge supressors will absorb some energy at your panel or meter if the lightning hits nearby and the energy not too great.
You used to be able to purchase such devices (Whole House Surge Suppressors) at Home Depot and such, but my local stores no longer carry them. I did, however, find them easily on the 'net. They are easy to install yourself, but the cost is only slightly less than the $100 fully installed price that you have been given. I have one (actually a second one on a sub-panel as well) and we've never had any damage, but my next door neighbor did. My GFI tripped on that hit, and that was all. Might have just been lucky, but maybe the supressor did help me out.
I cannot figure out what the $5/month covers, but I am not familiar with that particular system so I won't outright acuse it of being worthless (but I am skeptical).
When I was wiring my basement several years ago I researched this topic quite extensively and concluded, based on a study conducted by Florida State University, that the best protection was with a panel surge suppressor. A slight additional level of protection is achieved with point of use supressors, such as properly protected power strips, computer suppressor outlets, etc, but that additional benefit is pretty small, and the "insurance" such devices contain has never actually covered anybody via a paid claim that I could verify.
Bottom line is that pool electronics are no more or less susceptible to lightning damage, as a device anyways, than any other appliances in your house. But if you live in an area prone to lightning strikes, you should try to protect your electrical system and appliances.
