First think about the way you want to buy a domain:
Finally, be assured that all of the above is done in a very safe manner, because of escrow. When you bought a domain your money goes to no-one, not to the seller and not to the broker, before that domain is not in your name (possession). Only then the escrow money will be released to the seller of the domain name or to the domain broker that brokered the sale.
If you do have comments or questions please do not hesitate to contact me.