Hi-Blow when running at maximum depth will result in shorter times between rebuilds and maximum depth stress will shorten it's life span. Rebuild kits are expensive. HiBlows are designed for shallow lily ponds and septic tanks. IMO it is better up front to spend a little extra money for a unit that can better handle the 8.5 ft depth. Cheaper often ends up costing more money in long term.
If you are handy one can often buy the individual parts from different locations to lower the total cost. If you can figure out a way to not need the pump cabinet this will save significant dollars. Easy well ventilated pump cabinets can be built or one can use modified small dog houses or other box-like items.
Good air circulation (venting) is important for homemade pump shelters without an in shelter electric air mover.
Other places to cut cost is the weighted aeration tubing. Various types of hoses with homemade weight can save a lot of money. . Lots of aerators are sold using the cheap 1/2" ID black plastic pipe as airline; but note this pipe has an actual 5/8" ID. It takes around 1 brick every 4 to 6 ft to hold this airline on the bottom.
Strand cable or re-rod will also hold airline on the bottom. I have been using a good kink proof quality garden hose as aeration tubing for 21 years and it is still in very good condition and expect at least 10 more years from it.
Diffusers can be home made and save around $90-$100. Although there are a lot better homemade aerators than using PVC pipe with 1/16" holes as noted below. For starters use a 1/32" drill bit instead of 1/16". Smaller holes move more water. Homemade membrane diffusers are the best.
https://forums.pondboss.com/ubbthreads.php?ubb=showflat&Number=532880#Post532880Here in Colorado I run my aerator, a simple piece of PVC with 1/16th" holes drilled in it, 24/7 in winter.
All homemade aerator low cost items can be replaced later as more money is available.
