I really do not want to “burst your bubble” (who knows, maybe this will work-out well for you) - but let me give you my take on this. I am a “mid-level” eBay Seller with an established reputation (Feedback and DSR) and a decent following through my eBay Store and FB Page. Awhile back, I tried selling my Nintendo-Era Cards in similar lots - offering 100 Cards in NM/M Condition with a few Rare, Rev. Holo, Holo, and LV. X / EX Cards per lot. I forget the specifics on my lots as it was awhile back; however, in-order to be competitive with the “big guys” you really need to price the item well (similar to what they are selling for, or else nobody will buy them). Additionally, you will need to drive traffic to this listing - which usually involves slowly selling a few lots before your listing gains any attention. In regards to that, you are going to need to be patient until your listing gets going - builds-up views, watchers, and sales - this could take a few days, weeks, month… Don’t expect to start selling a couple lots everyday right out of the gate - simply not going to happen unless you offer something that nobody else is / can! This is especially true if you are new to eBay and don’t have that established reputation.
Secondly, you are going to have to take into consideration all of the eBay Fees / PayPal Fees, Shipping Supplies, Postage Cost… If you’re not already selling on eBay, you’re going to have to purchase all of your shipping supplies - which can be a somewhat large up-front cost depending on how you are planning to package/mail the lots.
Third, you are going to have to take into consideration all of your TIME! Personally, I run my eBay Business for fun while I am not working, so I never really factor this into my equation. However, if you’re working full-time and trying to do this on the side, that might be something you would want to consider. It is going to take you awhile to sort-through your cards, put together a few lots to get started (which will have to be done over-and-over again as they sell) and package/mail everything as orders come-in.
Finally, you will get those “idiot buyers” who either leave you a negative feedback and/or request a refund because they thought they would receive everything pictured. You could write the best description ever and you WILL still get these types of buyers - although, it does not happen that often.
Personally, I was not a fan of this type of business. I hated having to build the lots of cards (as it will take awhile) and packaging/mailing. Additionally, at the end of the day, I found that I could simply sell-off my bulk in either larger “small” lots (1K) or all together at once on eBay and still make $0.06 - $0.08 / Card! Finally, if you are in the U.S. you could even send all of your bulk into someone and receive booster boxes in return - which would sell much easier and much quicker!
Hope this helps - Sorry if I put a damper on your plan - just wanted to give you my 2-Cents!