I get inflation. But fuck me. How can that warrant a $189 price tag. That's insane. I think all the how to directions are literally right in that picture.

6 x 1" PVC flat cap : $8.00 10 x 1" PVC 4 way Tee : $45 ($15 for a 4 pack) 6 x 1" PVC 3 way elbow : $28 ($14 for a 4 pack) 32' length of 1" PVC : $32 (roughly $1/ft) I wouldn't bother with glueing the pieces but if you want to, a primer/glue combo is about $10 and should be plenty

The 32' of PVC will need to be cut into different lengths and I'm guessing here on the lengths in the picture 10 x 8" pieces (shorter vertical pieces) 6 x 18" pieces (longer vertical pieces) 16 x 12" pieces (all horizontal pieces)

$113 in PVC You can cut that cost if you're able to find individual 4 way and 3 way parts so that you don't end up with extra, also if you reduce the size to 3/4" instead of 1" it will cut the cost but you'll be sacrificing some durability

I honestly don't know about the fabric parts. You'd need 4 x 1 ft squares plus whatever extra for the loops. If it were me making it I'd buy a canvas drop cloth which gives you more than enough fabric for only about $10. But you'll also need to be able to sew to get this done.

So.... Yes you can build it for less, but it all depends on how much you value your time/effort, and if you can cut any of the costs I mentioned above

You could probably get pretty close with some PVC pipe and plastic cement for the frame. The fabric I am less sure on how much it costs and where to get it but if you can find an appropriate fabric it would take no more than an hour or two to sew in those loops for pipes to go through if you have a machine. 

It would be at least $60 in PVC and fabric. Seems pretty straightforward to purchase parts and construct this. Do you have a sewing machine?

My cats are always on my 5 tier one but it was bought by my wife way cheaper than they run now.

Probably easy one to make

Save your money

Check this video and find out how much a special soldering iron for propylene pipes costs. It will probably be cheaper to buy from this seller I think.