If you're interested - not to plug myself here, but I have 4 other m16 hicap mags available - prices aren't bad. $25 shipped for the 450rnd ICS, $23 shipped for a 300 rnd marui with some nicks and scratches, and $25 shipped ea for 2 near perfect marui 300rnd mags.
I can do a package deal - I'm wanting to goto locaps, but I know guys on budgets tend to gravitate toward the hicaps. I know you're new and young, and I'm just wanting to buy some new gear - so hit me up if you're interested.
But, as far as the mags you're considering, they're ABS plastic, and some ppl seem to really like them, others hate them (have read elsewhere). Personally, i wouldn't put plastic mags in my gun, would be afraid of them breaking as the mag seems to take the brunt of my abuse, but they ARE ABS.
I'm thinking of trying out a pack of STAR 30 rnd mags - $50 for 10 mags... - but can't justify it with 5 hicaps with over 1000 rnds available for me right now - along with the M14 I just bought...