This set is incredibly confusing to me. We have Holos/Reverse like Beedrill, which on eBay sold for 20-30$ (Reverse 2$) and then we have some outliers like Flareon Holo, which goes for 100$+ and Umbreon Reverse, which has been sold at 70$!
Can someone explain to me why some of the cards are so expensive when compared to others? Is there anything I’m missing?
As for what you are missing… it is the popularity of the Pokemon.
There are a hand full of Pokemon that a majority of people find appealing. The early eeveelutions are in that group. Beedrill just isn’t a very popular Pokemon compared to the eeveelutions. Combine rarity with a popular Pokemon and you get prices like the current price of a mint Gold Star Charizard.
I guess in the case of the mentioned cards it is justs the fact that some pokemons are far popular than others.
Eeveelutions in general are very popular and a lot of people collect them. Beedrill on the other hand doesn’t get as much love from collectors in general. People who go for the eeveelutions are competing with the people that go for them as well but they have to compete with skyridge set collectors, too. People who wants to complete a full holo set of skyridge will buy the beedrill too, but they don’t have to compete with many beedrill collectors I’d say.
So it just comes down to the popularity of the pokemon species and especially the eeveelutions being very popular among many people and therefore they hold a premium in price.
Edit: whoops, a bit too late 
Well there are the H series holos (H1-H32). Those typically command the biggest premium along with the Crystal cards.
Then there are the non-holo rares where you have the same cards as the H series but non-holo versions of each. (#1-35) These generally don’t command a high price but have been steadily rising along with all cards from this set.
Then there are the reverse holo rares. Same as the non-holo rares but they usually command a higher price than the non-holo counterparts. (#1-35)
Then… there are other cards like Pikachu & Oracle which are expensive and common/ uncommon. The reverse holos are very expensive.
Take a look at Bulbapedia to get a better idea of the set layout. I’d recommend reading about all the eSeries sets to get a better understanding of why they printed the cards the way they did:
bulbapedia.bulbagarden.net/wiki/Skyridge_(TCG)
Is that really the reason? Maybe I’m not entirely grasping the popularity of some mons, but I feel like Raichu, Gengar and Moltres are more popular Pokémon than Houndoom. Or at least comparable. Instead, Houndoom seems to command a much higher price. Is this really the entire reason for the inconsistent pricing?
@scratchdesk Yup, I’m aware of that, but that wasn’t my question, heh. Some of Holos or Reverse Holos beat out others of the same category by miles.
Thanks for the replies so far, guys!
Gengar is one of the most expensive holo’s in the set, it’s a very popular one aswell.
Houndoom is a very popular Pokemon, I’d say more popular to collectors than Raichu.
Plus you have to take in consideration the price of PSA 10’s.
Houndoom and Gengar are so expensive due to both their popularity and also the difficulty do get high grades on them. They both have alot of silver foil on the card making the cards very prone to scratching.
There’s alot of factors that need to be taken in consideration:
I think for this set especially, the card art is important due to the instagram appeal. The Houndoom card is pretty metal but the Raichu is derp af.
I’m seeing lots of Gengars for 50$, some better looking, some worse. Houndooms are exclusively 70-100+ ; Much higher than Gengar.
As I said the prices are also being influenced by supply and demand.
A few months ago there were nearly no Gengar’s on the market causing the price to go much higher than they are now, back then Houndooms were far more available. Now it’s the other way around.
Anyways, appears you know better than me, so why ask for advice on here if you are not willing to listen 
On top of the fan favourites, you also have to take into account the artwork on some of the cards. Some of the art for them were slacking in this set (like Raichu, Jolteon) and prices reflect that. But then you get some of them with beautiful artwork on top of that and they go stupid high (like Umbreon).
Well, ok, I guess that settles it, then, I guess. Thanks a lot for the various replies! 
Not much more to say than what other people have stated.
-Supply and demand
-Art
-Species
-Hard-earned high grades
Can only speculate about the factors that can be applied to a certain card, but imo these are the factors you should look at for explanations.