Online Marketplaces:
eBay – eBay is one of the largest and most well known online marketplaces. Baseball cards sell very well on eBay since there is a huge collector base actively looking on the site. To sell on eBay, you will need to take photos of each card, write detailed listings including card condition, year, team, etc. You can sell cards individually, in lots, or your entire collection at once. Shipping is extra so make sure to account for that in your pricing. eBay takes a 10% final value fee from sellers.
Sportlots – Sportlots is specifically tailored towards trading cards and is very popular with baseball card collectors. They have a large buyer base and can help you get top dollar for rare and valuable cards. Like eBay, you will need to photograph and write descriptions for each card or lot. Sportlots takes a similar 10-12% fee for completed sales. They also offer free expert grading verification to validate a card’s condition.
COMC (Cardboard Connection) – COMC has a large active marketplace for collectors. The big advantage over individual listings is you can send your entire collection to them. They will then photograph and list each item, storing your cards safely until sold. COMC takes a larger cut at 17.9% plus $0.49 per card for listing and order fulfillment. But it saves you a huge amount of time over individually listing hundreds of cards.
Local Sale Options:
Local card shops – Calling up or visiting local card shops is an option to get cash quickly rather than waiting for online sales. Shops need to make a profit though so will likely offer you 50-70% of estimated eBay values. It’s best to get quotes from multiple shops to get the best rate.
Sports card conventions/shows – There are frequently sports collectibles conventions held on weekends where many vendors set up tables. These are opportunities to display and negotiate sales of your cards in person. You’ll need to transport your collection safely and have a means to accept payments at the show. This is more work than online but cards may sell faster.
Consignment Sales:
Online consignment stores – Sites like Collectors Universe allow you to send your cards to them. They will handle photography, grading if needed, and listing cards for sale with their retailer network getting you the highest prices. Their cuts range from 15-30% depending on services used, but you let them do all the work.
Local card shops consignment – Inquire if your local shop allows you to leave cards there on consignment for them to sell over time. Shops typically take 30-50% commission if a card sells, but you won’t have to list anything yourself. Shops vet buyers so risk of unpaid sales is lower.
Facebook Groups and Forums:
Search for private trading card Facebook groups focused on your sport, team or player. Some have hundreds of active buyers & sellers. You’ll need to photograph and list your items for sale, and handle payments/shipping yourself if they sell. It takes more effort than a dedicated marketplace.
No matter where you sell, make sure to do research on current market prices, professionally photograph your cards front/back, accurately describe condition/details, package securely, and only accept secure payment methods. Building a seller rating and reputation takes time, so provide excellent buyer communication. With some work, your baseball card collection could earn you thousands depending on what hidden gems you may have. Let me know if any part of this answer needs further explanation.
