For a good cheap substitute, go to any middle eastern grocery for quince jam. My favourite is the Ayva Receli from Turtamek. Instead of a jam, this is a compote, Turkish style, with chewy slices of candied quince in a fragrant, heavy syrup.
La Bottega ottawafoodies.com/vendor/1173 in the market has quince paste in their jam section (look for a small rectangular flat block). I just bought one last month to try (it was from Portugal I think) - quite delicious. They also have quince jam which would probably work just as well as quince's high pectin content makes the jam quite...solid.
Another alternative is guava paste - the taste (and appearance ~ so nicely pink/orange) is very, very similar.
Grace on Bank Street ottawafoodies.com/vendor/1157 sells round flat tins of it.
When quince are in season, you can make your own;
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