If you're wanting a FA Tapu Lele, I would just hold the Espeon and buy one for $40. I myself was never a fan of trading a card and money for a single card. Since I'm more of a Pokémon collector than a player, I would hold on to that Espeon for as long as I could, especially since it is a 1st Edition. The value of Tapu Lele will eventually drop significantly, making your trade over priced in the future. Since it's the first Espeon printed (along with it's non-holo version from the same set) the value could increase more to what that Lele is worth now.
Older cards are mainly valued now for it's collecting purposes since most TCG events won't allow older cards to be played. Tapu Lele is only priced very high due to it's high use in Standard Format. Once a card comes along and completely obliterates Lele, or it's rotated out of Standard, the price could drop to 3/4 of what's it's worth now.
When I do trades, I tend to look at the long term effects of my trade. Since I don't build decks anymore, I look for trades that will benefit my collection. If I were to trade my 1st Edition Espeon for a Tapu Lele FA, then 2-3 years from now, I've screwed myself on the value of my collection.
If you do want to trade your Espeon, trade it for something that has equal value that will hold that value over time.
These are all my opinions so you can take them how you will.
