Costco (COST 0.42%) faces a bit of a dilemma when it comes to Black Friday -- and really, sales in general. The basic premise of the warehouse club is that members pay a fee to join and then get excellent prices in the chain's no-frills stores. In general, the company only marks its items up a limited amount, which makes it hard to offer sales on top of that. Costco is essentially a perpetual Black Friday for its members, and that has helped the chain steadily grow sales, members, and locations.
Still, while it offers good prices all year long, Costco attempts to step things up during the holiday season. To do that it brings in a wider selection of merchandise that meets holiday shopping needs.

Costco has already begun part of its Black Friday sale. Image source: Costco.
What is Costco doing?
The warehouse club has two separate "savings books." The first book has a wide selection of items, everything from the expected electronics to jewelry, gift card deals, clothing, and more. It's been available since Nov. 6, and the deals will continue through Nov. 26 (or until the company runs out of an item).
A smaller second sales book includes Thanksgiving Day online-only deals and other specials that run through Nov. 26. There are some online-only deals and some that only show members the price of an item when it's been added into their cart.
The deals offered in both books run the full gamut of Costco's diverse merchandise. Electronics are heavily represented, as are holiday food staples (and those are on sale now).
Costco's warehouses will remain closed on Thanksgiving itself. They will open at 9 a.m. on Black Friday and stay open until 8 p.m.
Some of the items listed on the chain's website are available to non-members with a 5% surcharge. Other items are marked "members only." Non-members can't purchase anything inside a Costco warehouse (though buying a gift card and using it to pay will allow a non-members to circumvent that rule).
A lot more of the same
Costco's deals are really about the changed mix of merchandise the company brings in, not prices. Yes, there are some deals that are better than they normally would be (likely due to the chain getting a better price when buying in higher-than-normal volume), but the retailer generally has good prices. The draw of its Black Friday sale is that members get to see what's new on the shelves (real and digital) -- and there are definitely some items being sold that aren't offered on a regular basis.