IP is indeed a bit of a barrier for awhile early on, I'm not saying it's unreasonable.
Eventually you'll get a handful of champs you love playing (and/or turn to ranked) and in the process of playing for fun/LP, you end up building a pile of IP almost by accident. It's like ok, you can afford another champ...but you don't really want to pick them since you're much more comfortable on your favourites, and eventually you get to the point where the IP cost of a champ isn't really a barrier.
I think lux is 3k-ish IP and was a champ I quickly become fond of early on. Nothing too crazy with her kit if you're looking for weird, but she's pretty easy to play if you just want a 3k champ to pick up.
That said, when IP is pretty tight early on, I'd be reluctant to buy champs for IP and discover that they don't click with you. Using refund tokens on IP seems a huge waste and I don't ever recommend it, so you'd basically be stuck with a champ you don't care for and need to save up again which is no fun. As such, I highly encourage making a habit of trying out the free week champs each week, and waiting for a champ that interests you to show up there before trying them, so you know first hand that you like the way the champ plays.
.....they really switch it up with new mechanics like turrets and stationary items that do...things. 
and I don't want to use one of my refunds so maybe some players that have actually played the 3K IP champs can help me pick!
