You have 2 choices, and you may want to discuss with your Adagio consultant to determine if either work well for you.

One choice is the Alternative Price List items that you mentioned. This allows you to create additional pricing schemes with a separate list of base price and A-E customer pricing, identical to what you currently use for pricing from the master IC items.

You can create (essentially) unlimited numbers of alternate prices for each item. You may choose to create a Price List code for general blocks of customers, or create a separate Price List for every customer (ie create a price list code for each customer if desired). You don't have to create alternate price list items for every item for every customer, just those that are different from the master pricing you currently have set up.

Alternate Price Lists work better in high-volume sites with lots of item SKUs because you can export/import the alternate prices for easier maintenance.

The other choice is Special Prices that are defined in Order Entry. A record is created for a customer to give a particular price for a specific item or any item within a specific category. You can assign a particular price, a particular A-E customer price (either from the master list or from an alternative price list) or a particular amount or percentage discount (or markup, if the item uses markups instead of discounts).

These special prices cannot be imported so they can be a little harder to maintain if there are a lot of them. One big advantage is that OE 81C has an option to 'Always use special price', so when a customer orders the item, they will always get the special price regardless if the item is on sale or another price may be lower.

If you always want to ensure that Joe buys the widget for $15 and Sally buys it for $20, you can use either method. OE Special Prices may be the better way to go, because Alternate Price List items are always a Discount on base price (or Markup over the markup cost) and if the calculated price was less then the agreed-to price, that calculated price would be the default. But the choice is up to you.