League of Legends (LoL) Question: How much is it for a full Tier 3 Rune page?

~22.000 IP for both AD and AP page, I guess.

It costs a lot but it is well worth the investment to get some standard rune page for ad and ap. Standard would be Greater Glyph of Magic Resist (205x9=1845) Greater Seal of Armor (205x9=1845) Greater Quintessence of Ability Power (1025x3=3075) Greater Quintessence of Attack Damage (1025x3=3075) Greater Mark of Attack Damage (205x9=1845) Greater Mark of Magic Penetration (410*9=3690). Total Cost = 1845+1845+3075+3075+1845+3690 = 15375 for a standard AP and AD page. I would recommend buying what you can and not buying champions until you get them. It gives you a huge advantage having them, or is a big disadvantage if you don't. Hope this helps.

min 7.080 IP (example: glyphs, marks and seals = 205 IP | Essences = 515 IP)
max 28.290 IP (example: glyphs, marks and seals = 820 IP | Essences = 2050 IP)

so one balanced/whole/good runepage is 21.210 IP

I think 8-9k EP for one runepage ;)

Consider finishing your rune pages and buying new ones before buying champions. Also, try not to play any ranked games if you dont have a rune page dedicated for that role. Yeah, runes cost a lot.