You won't see these things coming and you won't be happy when they show up.
The 'Support Plan Trap'
When asked about the 'annual support plan' some vendors will outright lie about it, saying that the payment for 'annual support' is optional. As those words leave their mouths they have an obligation to explain the consequences of NOT paying the fee which are 1) support in all forms will be denied, and 2) software updates (which are essential) will be held hostage.
Best Consignment Shop Software may be the only vendor that passes ownership of the copy of the software to the user. To give the illusion of matching the offer, some vendors once again lie about their policies. They say "Oh yes, you can resell the software" without again fulfilling the obligation of explaining the details, which are 1) if you found someone to purchase the software, the vendor is going to take most of the sales proceeds as a 'commission' or 2) the software can only be sold to the person buying your business who MUST continue to use the exact same store name, location, address and phone number.
See how this works? There's much more...
Oh that sales person sounds oh so friendly on the phone. Those email promises are just what you're looking for and don't you know that the competitor that is being bashed is completely deserving? In the consignment-software arena, some vendors count on foolishly-placed trust, failure to pay attention to detail, impatience, distractions, and all else that can make one gullible. Bashing competitors is a favorite pastime in this group so perhaps it would pay dividends to pay attention to who is doing the bashing - and why.
Think ahead. Once you've purchased a program and spent a fair amount of time and effort learning it, you won't readily jump to another program once you discover what should have caught your attention the first time around. You'll be locked in. Vendors have been practicing and fine tuning the art of bilking customer years before you came along. They are experts at it! They think they know just how much they can push the deception game and their escape routes are planned out and well traveled. Common sense will tell you that getting into a software program with a monthly or annual fee will assure that you will be paying higher fees later on. Count on it. Every person who has come before you has had this experience.
Bad People: Bad Policies
Looking at a website, listening to a fast-talking sales person and buying into the façade will land you in a relationship with one person (not a company) who makes up things as he goes along. The prime example is who has 'fired' customers when he decided they asked too many questions. He offered a 'free update' to a group of users who fell into the optional-annual-fee ruse, planted a bug in the update to disable their program and refused to remove the planted bug until they agreed to pay the ransom. Stay away.