In terms of value, I think that ebay-searching is likely your best research tool. The Lionel HO cars look to be in great shape, and you have all of the original boxes (also in great shape), so the tally might be surprising.
You may already know this, but if you're logged into eBay, you can type in a search phrase, then (in advance search tool) click on "completed listings" ... both those that did sell, and those that didn't. I find this tool most helpful to get a better stap at a "high/low" range for value estimates.
And remember ... in many cases, if things are not all that common, that can reflect in a higher market value.