You should never ever go to the US without insurance. Medical costs are horrendous. The travel agent is I think within its rights to make it a condition of selling you a ticket, but you don't have to buy insurance from them (indeed, I would urge you not to, as it is generally quite expensive). Shop around for yourself, then take the policy to the agent and get your tickets.
The agent has no right ot insist you get insurance from them.
They didn't force there insurance, any would do!
For sure I won't be buying insurance for 5 days from them at €45...
I'll check out getcover.com in the meantime is there any other I should get quotes from?