I paid US$80 online for my Acerbis hand guards. Please note that these have a strong aluminum (aluminium to you) spine that connects at two points: the bar end and inside the lever mounts. This protects your levers when the bike is dropped. From what I can see online, the Polisports that you mention will block wind, but surely will snap off (along with your levers) if (when) you drop your bike or crash. To call the Acerbis guards a "hand guard" is a misnomer; they do protect your hands from brush and wind, but far more importantly they protect your levers in a fall.

Believe me, you don't want to be stuck in the wild with a broken clutch lever.

My KLR650 clutch cable snapped (due to corrosion and age) during a ride on Saturday, and I had to drive 40 miles to get to a shop where I could get it repaired, and that ride included probably 20 stop lights and about 15 miles in manic 80mph traffic on I-80, one of California's craziest corridors. Yes, a motorcycle can be ridden without using the clutch but it's not easy, especially the starting, and the keeping the bike running when you are forced to stop. You'll hope all the stop lights are at the top of hills!

cheers