You can run it like that, with one pump as recirculating and one acting as a feed pump. However, if you use the extra $30 feed pump you get 2 pumps acting as recirculating and will get better performance. Plus, a recirculating skimmer is not affected by changes in water level.......so a poweroutage/feeding/return pump failure would not make the skimmer overflow like it does with the non-recirculating in-sump skimmers.
Another good thing about Avast skimmers (other than them being local manufacturers and members of WAMAS), is that they use the PSK pumps. I don't care how good a pump is.........they fail. It could be a fluke, manufacturer design, or the day it goes out of warranty it just decides to crap out. The PSK1000 pumps are very energy efficient and inexpensive. While DC pumps are energy efficient, they cost a lot more and there have been some issues with them.
Do yourself a favor and go with Avast.