Another thing you can try is breeding. Get Ditto(or any MALE pokemon in the Field egg group), any Eevee, and put them into the Daycare Center located in Solaceon town. If you have it, switch to the Poketch app called the "Day Care Checker". Click Here To See Info For The Day Care Checker On Bulbapedia. After switching that on and putting the pokemon in the Daycare, just start running around Sinnoh until it shows there is an egg to pick up at the Daycare. Fly to Solaceon Town, or walk, and go speak to the man in the front of the Daycare. Make sure you have an empty space, then say "Yes" when he asks you do you want the egg. Then just run around Sinnoh until the egg hatches. There you go! A new eevee! Repeat the process to get more eevees, soon you will have enough to get all the eeveelutions!