The C&V forum is full of people who hate the "what's my bike worth" question. Best way to determine market value is to go to ebay and do a search for your bike in auctions that have already closed. This'll give you an idea of worth. But there is a distinction between what someone will pay and the intrinsic value of the bike - e.g., I'd probably have to pay at least twice what my custom made Stan Pike would bring at sale if I wanted to purchase a factory built modern bike that would be in the same class.
Sight unseen, not knowing much about the components on your International, it could go for anywhere north of $275. But it will pay you to do some research to see what a bike with your component set is going for in CL and ebay. There's a bunch of flippers waiting to buy nice old bikes for a song, then do a minor tune and sell it to make a livelihood or boat payment. Or they disassemble the bike
and sell the components to maximize their profit. (for instance, in Philly, a shop wanted $200 just for the Campy NR cranks, not even the entire bottom bracket set, and it was well used!) Your International has one of these, no? So take your time selling your beloved steeds. Sure, they are not modern, but both these bikes are incredibly durable, unlike their modern counterparts.
The International was a great bike.
. The Sports - I still ride mine. These British Steel bikes are becoming rare and are much sought after!
Although it looks like my long distance riding days are numbered due to arthritis, I will still hold on to my bikes and ride them until I cannot - the exercise is precious, however frail I may be. When I sell, my aim will be to find someone who wants to ride the bikes I own, not merely profit from them.
Depending on where you live, Craigs List may be easier for you to sell your bikes if you don't want to pay for professionally packing your bike to ship. But then, there are colllectors from Japan snapping up bikes on ebay all the time - if you want top dollar. It is tricky to become ebay-savvy instantly though.