The chassis is around $1,200, but I can get a chassis with a 2tb/s back plane for around $2k that supports up to 144 1gb Ethernet ports, but the line cards get you. When I looked up pricing for ZyXEL VDSL2 line cards, I was seeing "new" prices of over $5.5k for 48 ports from many retailers. That's about $100 per port, so about on-par with 1gb fiber. The 1gb DSL will probably be a lot more expensive. You can probably get used VDSL2 line cards for your $900 price, but you're not going to have that benefit with the new 1gb DSL.
The bigger issue is the range. the 1gb DSL only has a 100m-200m effective range. 250m is the best and will rarely happen. DSL also consumes a lot more power, almost a magnitude more when you include everything.
The other issue is the uplink ports. I can get a 1gb fiber port with a 20km range that uses 0.5watts max for about $100 on my switch at home. 10gb ports, start around $2k for 100m stretches, and get up to $5k quickly when you need distances in km units. These DSL boxes with 1gb ports are going to need 10gb uplinks if they want to even remotely handle the rates they claim. I bet you're going to be looking at $10k for a line card and $5k for the uplinks. That's already $15k.