Many people who paid in advance part or all of the price of their telescopes were left with nothing, and received no refunds. Indeed, some people were even told that they had to pay the balance of their orders prior to delivery, even though the Coulter employees telling them this knew that they probably wouldn't be able to fill the order. This was a sad ending to a company that had dealt fairly and honestly with its customers for years. Some mail order telescope makers are large companies that have been in business for many years. Some are small time operators.
Bigger companies are less likely to fold up, but also tend to charge more.
Choose which is most important for you. The bankruptcy of Coulter Optical was rather unusual and unexpected. Don't be paranoid, but also don't be gullible. Many thousands of people have purchased their telescopes through the mail and have been very satisfied. You can find some great deals in used telescopes.