First, be prepared to negotiate. For most business opportunities, you will be absolutely amazed to see the purchase price drop if you ask for a lower price. Try an approach like this: "I would love to buy this package. It sounds like it is exactly what I have been looking for, but it is slightly out of my price range. Would you consider accepting $2,000 instead of the $3,500 asking price?" Then, be prepared to meet them somewhere in the middle--but do not allow yourself to be talked into paying top dollar. Remember the strength of all good negotiators: Always be prepared to walk away from the deal. Odds are, the seller will not want you to walk away. Make an offer and see what happens!
Once you have settled on a price, ask the seller if the sale can be broken into installments. Not only will this make the payments easier for you, it will protect you if the seller does not deliver the promised products or services. If you are disappointed, cancel all subsequent payments and ask for a refund of your initial installment.
Use credit cards, not cash or personal checks to pay. If there is a problem or you get "buyer's remorse," you can often refuse delivery or return the products purchased and ask the credit-card company to deny or reverse the charge to your card. The company then charges the expense back to the account of the seller. If you pay cash or write a check, there is no such recourse.