Flying Scotsman still takes Paypal. The new owner is pretty good, but e-mail before ordering.
Internet Trains takes Paypal as well, but they are sloooooooooooowwwwww......
Internet Hobbies - they list everything, but not everything is in stock. They screwed me on a coupon once, so they lost my business. Your luck may vary.
Valley Model Trains - slightly higher prices, but good service.
As a side note, a credit card order is MUCH safer than Paypal. If your order is lost, damaged, incorrect, wrong amount charged, whatever, your credit card company will go to bat for you. Paypal will not... And most times, credit cards are not charged until your order is shipped. Paypal is immediate.
Hope that helps...
Scott