you can just get any python be it the 20foot or just the parts themselves.
Petco actually sells the parts for the python so you can pick that up, then visit a local homedepot and get as many feet of clear hose as you like..
You can get all the parts, save two, at a Lowe's... or maybe Depot too, though their hoses connections are more limited...
Two parts you can't find in my local Depot/Lowes:
The gravel vac piece itself, buy the cheapest one you can find, without a siphon trap...
And a "water Bed drain and fill kit". Found mine at a local hardware store. 5 or 6 bucks - this is the piece that hooks to the faucet.
Use tubing that matches the hose repair stuff found in the garden section at depot and lowes for your connections along with an inline cutoff valve (also found in garden section), and voila, Python, made.