Unigine

[Diesel]

There is a new Unigine demo available for a while: http://unigine.com/press-releases/080904-tropics/

Plus there are special prices on Unigine for indie developers, starting from $4990 (or $1985/month during 3 months) for binary version and $9980 (or $4990/month during 2 months) for source one: http://unigine.com/licensing/

[Hypnotron]

these "special prices" are just the down payment.  Another $20k or $30k is due prior to commercial release for the binary and source versions respectively. 

"The first part of the price is an initial payment, the second one is to be paid after getting funding from any kind of investor or before official release of the Unigine-based product. "