At the grocery store, a banana is a banana -- it costs $0.89/lb, and the store's CoGS is $0.69/lb. Car dealers are different -- they don't make money on the car, they make it on the other stuff that the salesman peddles. Thus, no price list.

Software is the same way. Salesmen are there to spot opportunities and get a solution out to the customer. You may sign up for payroll services online, and not realize that for an additional $X/mo, you can get some sort of expensive regulatory requirement handled as well.

If you're dumb, and buy a $200 HDMI cable, how is a web form going to stop you from making poor decisions. A typical startup pricing page has 3-5 plan options.