Have you decided what period you want to collect? Do you want to collect all the way to the present day? Or would you be happy assigning yourself an end date of some sort, say 2000 or 2005? There are quite a few US collectors in the forum who end their collections about then, when US stamp issues got too mickey mouse for them.
Your answer here might help focus on the particular characteristics you are looking for in an album lot or accumulation (or two) that you can take over and use as the foundation of your own collection.
Many of the album lots on eBay
for US mint run up to the period of late 60s to 1980 or so. A number do continue after say 1985, but not nearly as many as those which end sometime about or before 1980-85. So if you want to get going sooner, rather than later on your collection, there are quite a few pre 1980 collections that are viable as cost effective ways to found a collection intended to run to say 1990 or even 2000.
But if you want to collect all the way to the present day, there are fewer such lots on eBay
that run to say 2015 or even 2010, and the prices reflect the much higher face values involved. For this, you will need to be patient and then bid decisively to get the lot you really want.
I suspect you will want to buy the Mystic hingeless albums now from Mystic to suit your collecting period and end point. Doesn't look as though these are on eBay
in any real number at all. You would then be transferring from the source album into yours, identifying the stamps as you go (you should re-confirm the ids made in the source collection).
Hope this helps.