If it's legit, YES!!... 35 for any Avalanche C4 is a screaming deal, let alone a current model year (well, at least for a few more days).
For reference, our dealership here is selling 06s moderately equipped for around 50.
I love my Avalanche... throws a fantastic wake for both boarding and surfing. Wakeboarding wake is somewhere between a Malibu and a Nautique... longer ramp and transition at the bottom with a good amount of kick at the lip. Surf wake is large and glassy (if you weight it right), although you have to put more weight in the front/ride it a bit faster if you want a longer pocket...
I love my Avalanche, and you cannot beat that price... if you have any questions, shoot em my direction, and I'll see if I can answer them!