Price of cosmetics: Sure, they can be somewhat pricey, but it's important to remember that it is a free game and entirely unnecessary when it comes to gameplay. The cost of a normal skin at release is 975IP, which equates to roughly £5.50 (so around $8.45 or 7.50 euros). Yes, legendary and ultimate skins get very pricey but there are plenty of good skins out there for the normal (and lower) prices. When you compare the cosmetics to a game like CS;GO, where knife skins can cost in excess of £200, it's actually not a bad break.
IP Cost at release: To be honest, I don't personally see this as a problem, as I usually play enough games inbetween champion releases to earn enough IP to buy the champ on release. While I can understand this is still inferior to an open roster, the costs could be far more substantial.
Level 30: If you work at it, it shouldn't take very long considering you've already played the game for a time before. Does your old account not work anymore?
Champs and runes: There are champions out there such as Annie, Master Yi etc (full list of 450IP champions here:
http://leagueoflegends.wikia.com/wiki/Category:450_IP_champion) who cost a mere 450IP (two games worth easily) and are very much viable champions. Getting someone you like and carrying them back up to level 30 will not be difficult at all.