Elder Scrolls Online: Tamriel Unlimited is buy-to-play, which means you fork out $59.99 for it on Steam or another outlet and, unless you wish otherwise, you never have to spend another penny on it again. It's a model that's probably most famously associated with Guild Wars 2, which helped establish the model as a viable "middle way" between subscriptions and the free-to-play model (which too often features noxious and distracting microtransactions).
Much like Guild Wars 2, Elder Scrolls Online: Tamriel Unlimited makes up for the loss of a subscription with a cash shop, here called the "Crown Store." Compared to that found in, say, Star Wars: The Old Republic, it's a fairly benign model, as most of the options focus on cosmetic options such as costumes and mounts rather than game-altering bonuses.
Game-altering bonuses do exist, but you're not going to find a godly "Sword of a Thousand Truths" or some such that makes you significantly more powerful than other players. All of the bonuses fall into the "Consumables" section of the Crown Store, and they're essentially convenience versions of items you can get in-game with a teensy bit more effort. You can buy food, for instance, that increases your health, stamina, or magicka for two hours (although ESO wisely caps the bonuses at Veteran Rank 10). You'll find scrolls that allow you to respec your skills or attribute points, but you can also pay for these services in-game for a reasonable amount of gold.
Most notably, the Crown Store lets you pay for crafting motifs that let you make armor and weapons in the styles of the game's various races ,if you don't want to waste time digging for them in Tamriel's chests and drawers. The catch is that the rarest ones (Dwemer and Imperial) are breathtakingly expensive at 5,000 crowns each. That's roughly in the neighborhood of $35.00 USD.
Unfortunately, the Crown Store is probably best defined at this point by what it doesn't have. It features costumes that make your character look like he or she's wearing an entirely different set of gear, for instance, but the current costumes are all boring, drab affairs that look like what you'd find on the random NPC faction guards in-game. In every case, you can craft versions that look significantly better. The rest of the store is devoted to mounts and quirky, non-combat pets, such as a Daedric Scamp or a Windhelm Wolfhound that looks like the dogs in Skyrim.
Compared to the items for sale in Guild Wars 2's similar cash shop, this is boring stuff. With the exception of the guar mounts, none of the cosmetic options looks much more appealing than what you'd find in the game itself. Missing in action, for example, is any method of renaming your character or remedying some unfortunate accidents or oversights that might have occurred in the character creator.
It’s a double-edged sword - ESO’s paid items might be pretty boring, but this at least means no one will ever feel forced to use it.
The subscription option still exists, though--although now it's known as "ESO Plus." It'll still set you back $14.99 per month, but that money now gives you 1,500 crowns to spend per month. It also grants you a series of hefty bonuses, such as:
10% bonus to experience point gain
10% bonus to the time it take you to research new items for crafting
10% bonus to the "inspiration" you get while deconstructing and crafting new items
10% bonus to gold acquisition
Those are considerable improvements over the core game, and I suppose the bonus to gold acquisition might be enough to trigger cries of "pay to win" in some players. On the flip side, so much of ESO revolves around the possibility of crafting your own gear that I can't see it making that much of a difference.