I would be more upset about the leak than the $45 they want for the board...
Not sure that taking the hit on a trade-in would be worth it over $45. I get your point on the cost of the board, but I work in a business where we make / sell OEM parts and aftermarket replacements. We normally sell 100+ in a shipment. When somebody needs one piece of something for a repair, it gets expensive. You have the cost of the time inolved to take an order - look up / verify you have the right part, create the paperwork to make it if its not in stock, have somebody get it, pack it, do the paperwork to ship it, process the payment and take the hit for the credit card fee.
On these jobs the cost of the part is far less than all the other costs that go into getting it out the door. Can't count how many times I had to listen to somebody who is unhappy with a minimum order charge and its for some little item that we aren't going to make any money on and really don't want to deal with. Having been on both ends of these deals - I don't think anybody is real happy, but unless it's something you can make/repair/buy used, there isn't really much anybody can do.
2005 F-150 FX4
2013 Rockwood Roo 23 IKSS