Unless it's a scoped WWII sniper model or a Jungle Carbine, $300 is about what these are worth in nice condition, matching numbers, good wood, etc. WWII L-Es with 'US Property' markings are Lend-Lease, made by Savage Arms. The Canadian makes are collectable in Canada, not so much here.
Condition is everything, like location to a realtor or business. The finish should be black blue, the correct British coloring, and just about intact. Markings should be clear, and no re-paint over the old. Bores can be a bit dark, but strong, no pitting, and bolts need to be headspaces correctly and match the rifle. Wood needs to be color matched and without defect or cracks, just normal dings. Arsenal repairs are OK, but not obvious.