Wow.
Everyone complains about the high prices of ponies and other merch in this game - mostly ponies - because the only way to get a pony after a while is to flat out buy in game currency to then buy a pony. There are two types of in game currency; gems and bits. Gems are by far the harder to obtain, and you can earn them or buy them. (The smallest purchase pack for gems is 20 gems/$1.99... The largest is 1680/$99.99)
... And, personally, it's all about the ponies. In my G1 collection, for example, (the ones from the 80's) I have around 450 unique production ponies. In the last game expansion to the Crystal Empire, there were two VIP collection ponies, one for 750 gems and the other 900. That means that for $100, I can have bragging rights for just one of those digital VIP ponies. Or, if I own a gem producing shop or two and can sit on my hands, I can wait a couple of months until I produce 900 gems. Gem producing shops typically only produce 1-2 gems a day, so at best, it would take 2 1/2 years to produce enough gems for the most expensive of the two. (To my knowledge, there are only three gem producing shops) Right...
So imagine my surprise when, not five minutes into game play, a screen flashes up with the offer of a pony, 10,000 bits, and a bit of decor, for $0.99. NINETY NINE CENTS. Say WHAT!?
My first mistake was not taking a screen shot. Who would believe me? So I wised up the next time. Next came Architecture Unicorn, a Canterlot pony - unlocked in level 25, then Fashionable Unicorn, also a Canterlot pony. The least expensive flash offer I received was for Nurse Redheart, who is only available in a bundle, for $1.99.
Of these flash offers, the best is probably Nurse Redheart. Not only is she the obviously least expensive, but she comes with a shop that is very expensive. As a new player, hearts are a nice commodity to have, but they quickly loose their value after the purchase of Zecora (30 hearts) and Hoity Toity (70 hearts). Yes, you can use them for the Balloon pop, but be prepared to be well stocked for Sweet Apple Acres in wells, barns and rodeo enclosures. There have not been any other heart based purchases in a game update since I started playing in 2015. It is a shame, as hearts are often offered in solo events. My last account had 500+ hearts racked up. I really didn't need another well or rodeo enclosure taking up space in my inventory.
I can't recall seeing ponies offered for a flash price *that* low. Maybe someone has been listening? It's difficult to say...
*EDIT*
As I have been leveling up and unlocking ponies, it turns out there are a few others available to buy for hearts, and I believe one of them is a potential Ponyville community must have, Mayor Mare. Also available in the Ponyville community, along with the aforementioned Mayor Mare, Zecora and Hoity Toity, is Jeff Letrotski. I feel like this is a pun for something - The Big Lebowski? - but I'm not sure.

The only for hearts purchase that is not in the Ponyville community can be found in Sweet Apple Acres. Uncle Orange is somehow, likely from her mother's side, related to Applejack. It is interesting to note that it sounds as though the order of expansions to different areas started with Sweet Apple Acres, and then Canterlot, then The Everfree Forest, and now most recently The Crystal Empire. After the expansion to Sweet Apple Acres, the hearts were aparently abandoned as a means of buying ponies; there are no heart gem ponies available in Canterlot nor the Crystal Empire. Hearts are earned through participating social activities; I'm not sure why they were abandoned, but I stand by staying that after the purchase of these ponies, heart gems are useless, and either they should be removed from the game, or they should have purchasing power.