Ya I personally wouldn't get that much RP. Get enough rRP to purchase 3 or 4 champs then get an IP boost.
Elise is one of the best champs in the game. She is also one of the hardest to play and build. I know this because she is one of the top 3 champs I play. I personally like playing high risk squishy complicated champs but Elise is not for someone new. Please listen to me on this.
Elise is on the free rotation right now so try her out abunch before buying her.
You really need to identify your play style and buy champs based on your style. Don't buy champs based on looks. Singed looks really dumb ingame and his artwork but he owns, this is just one example. Heres another example, Syndra looks super cool but isn't really that good and very rarely gets picked.
I suggest checking out champs that are classified as tier 1 and tier 2 as they are the most competitive.
I said this already but really want to stress this, pick champs based on your play style. I always do looks of research on a champ before I buy them. I watch videos to see how they are used and look up builds for them. I also ask other players to tell me about the champs I am interested in and always look for useful solid knowledge about the champ.
Mobafire.com is a great and easy website where you can find good builds and extensive guides for every champ.
Solomid.net also has builds and guides and even has info on which lanes a champ is strong in. Furthermore, they even show you which champs counter other champs and show which ones they are strong and weak against.
I personally know how bad it sux to buy a champ and then suck with that champ and then get super pissed cuz I just wasted money on a champ that doesn't even fit my style. Some champs, like Elise, Anivia, and Oriana have very specific style you MUST play them with and if you don't you won't do any damage all game and likely feed, then after the game your team will report you and you could potentially be banned :/
Test out the free champs to see which ones you do best with. Find your style then come back here and ask which champs fit your style and we will be glad to help you.