Good cheddar is common in Canadian markets. Balderson (Canadian) comes in 1, 2, 3 and 5 year; the latter is a bit too strong for me.

Armstrong cheeses are good value. Their cheddar blocks come in extra old, old, medium and mild (we use the two oldest, excellent value. Their extra old has no coloring.
They also make some light cheeses.
Here is the Armstrong "gourmet grilled cheese recipe:

8 slices multigrain bread
260 g Armstrong cheese, freshly grated
Olive tomato spread

Olive tomato spread:
100 grams pitted black olives
1 roasted garlic clove
8 medium semi-dry tomatoes
5 teaspoons (25 ml) olive oil
10 fresh leaves, flat-leaf parsley
1/4 zest of lemon
Combine in food processor to light, chunky texture.

Assembly-
Lightly spread butter n both sides of bread.
On the inside of one slice, coat evenly with a small amount of the tomato-olive mixture. On the same slice grate cheddar (about 65 gram)
and close the sandwich.
Place buttered sides down in a frying pan at low heat until both sides are crisp and golden brown. Cut in half and serve.