Yes an Atlas is certainly a desirable model, the price of course can vary widely due to condition, and I can't really say what the average price is where you live, but the asking price for a good restored one in the UK I would expect to be somewhere around the £3,500-4,000GBP. I hope your wife is able to kick start a 750cc bike OK? The early ones had low compression pistons as standard, the later ones did not!