Kirstin, All else being equal (it never is!) a matched numbers bike will command a higher price than a mismatched one, however these are not very expensive bikes compared to some other classics - My own observation is that good ones seem to be available for between $5,000 to $8,000 - so there might be a difference of $1,000 or so for a good runner with mismatched components (the gearboxes on Commandos are also numbered at the top, so you can see whether this matches either the frame or the engine). Rennie has already given useful information regarding earlier and later models etc. However what you will find by reading through this and other forums is that people don't just collect Commandos they ride them, regularly and far and quickly, so it is important that you first and foremost get a good one, regardless of it's purported provenance. Do try to post some pictures as there is much that can be discerned from a simple photo. I would try to find someone in your area that has some knowledge of Commandos and bring them along when you buy your bike, also I would consider buying from a British bike dealer if there is one in your area. Good luck with your search, you will undoubtedly enjoy owning and riding a Commando.