OTOH, you don't say who made it, so...
If it's a GI gun and in decent shape - ie, not shot out - that's one heck of a good deal! Even if it is a shot-out beater, that's a great deal. If it's a Winnie or Rock Ola, it's a super-duper deal.
No expert on them, but other brands probably fetch a few $$ too. Jouster might have specific info on the various brands.
If it's a collectible and rings your bell, you could probably find a replacement barrel on line or from a collector's org and get her in tip-top shape.
Hope you're on to something good - they're a fun little gun to shoot!