Reddit mentions of Golf Net Lacrosse, Cage, Hockey and Sports Netting, Fishing Nets Choose Your Length. (4' X 12')

I'm a very avid DIY'er but I don't think that price is out of the question nearly to the extent people are complaining about it.

Angle iron (What the stand is made out of), 20$: http://www.homedepot.com/p/Everbilt-1-in-x-96-in-Aluminum-Square-Tube-with-1-20-in-Thick-802537/204273939 Edit: It's just more 1x4s, my mistake - total cost below updated (2x @ 4$).

Not the shittiest/cheapest you can find Plywood? ~20$: http://www.homedepot.com/p/Sande-Plywood-Common-1-4-in-x-4-ft-x-8-ft-Actual-0-205-in-x-48-in-x-96-in-479023/100073744

Paint - White and Green (Lettering): Seems easy enough to get away with the cheapest stuff here, so: 8$ (2x "Sample Sizes" @ 3.94$ from Home Depot, probably would need 2x "sample sizes" for the white, but I'll stay conservative).

Chipping Matt x2 - ~20$/ea: https://www.amazon.com/s/ref=sr_st_price-asc-rank?keywords=Chipping+Mat&rh=i%3Aaps%2Ck%3AChipping+Mat&qid=1495570282&sort=price-asc-rank - Yes, I know you could buy a set of putting carpet for cheaper and cut it up, but chipping matts are significantly stronger than regular putting green surfaces, and realistically a "good" quality one should cost you at least ~25$.

Turf for the surface (Cheapest available, frankly I feel like theirs seems a little more padded than this, but for the purpose of costs...) ~21$: https://www.amazon.com/GREENSCAPES-209107-Grass-Rug-6-Feet/dp/B00LK2MIFC/ref=sr_1_2?ie=UTF8&qid=1495570789&sr=8-2&keywords=Putting+Turf

1x4s for framing 4$x2 (One for each setup) Edit: : http://www.homedepot.com/p/1-in-x-4-in-x-8-ft-Premium-Kiln-Dried-Square-Edge-Whitewood-Common-Board-914681/100023465

Foam Balls (Lowest quality possible), ~12$ - didn't search too hard, but couldn't find less than a 12ct (And who wouldn't want a few spares with something like this): https://www.amazon.com/PrideSports-Practice-Balls-Count-Yellow/dp/B00466W9X0/ref=sr_1_1?ie=UTF8&qid=1495570456&sr=8-1&keywords=Foam+Golf+Balls

Netting (Cheapest comparable that I found), ~12$: https://www.amazon.com/Lacrosse-Netting-Fishing-Nets-Length/dp/B013W40VS6/ref=sr_1_7?ie=UTF8&qid=1495570637&sr=8-7&keywords=Netting

So all in all we're at 125$ not including any hardware (screws, nuts/bolts, brackets, etc) nor the tools that you might require to assemble the thing. You could also probably safely assume a shipping charge in the range of 20-40$ trying to mail a setup like this.

Sure, the guys making these things are buying in bulk and very likely aren't paying retail, but you would be paying retail prices. Let's also just forget the fact that all of the above doesn't account for any mistakes you might make along the way, requiring re-purchasing goods.

Frankly, I don't think this is a very good DIY project at all.

Edit: You could get away with "Two sheets of plywood" like you said (For the legs, frame, etc), but you'd want to buy much beefier stuff (~1/2" at least, 3/4" preferred): http://www.homedepot.com/p/Sande-Plywood-Common-1-2-in-x-4-ft-x-8-ft-Actual-0-472-in-x-48-in-x-96-in-454532/100017950 - There's also Softwood Ply and Particleboard available, but frankly, I wouldn't touch the stuff (ESPECIALLY the latter) if I had any intention of using these on beaches, etc.

Edit2: Just noticed these things are plastic: https://cdn.shopify.com/s/files/1/1557/3333/products/products_chippo_4_800x.jpg?v=1495158893

Whelp, fuck 'em. Looks like I'll be making my 150$ counterparts instead.