My former company (AeroFS) was one of the few I'm aware of that was willing to hire good talent even if it required a visa.

Also, I think that asking someone from India (taking that country as an example) to move to the US for less than market wage to toss the dice on a startup is... a challenge. That startup is less marketable on their resume than BigCorp if they want to return to India and get hired by another company or join an outsourcing company.