Tier 2 runes are garbage. Tier 1 runes are pretty good though, as they have half of the stats of Tier 3 runes at less than 10% of the cost.

Sometimes I go yellow AND blue runes mp5 @ 18 just to be able to shoot a volley every 3.88 sec, never run out of mana.

doing runes right as ashe:

marks: Arp
seals: manareg/lvl (don't buy any manareg items on ashe please, these are enough)
glyphs: cdred/lvl (the idea of getting raw maxmana instead ain't bad though)
quints: depends on what you want - high early game strenght: get the + raw Damage ones, otherwise Arp again

edit: and yeah get tier 1 runes until you're lvl 20 then only buy tier 3 ones
(and don't care about the price of tier 3 runes only be sure they are the best you can get, there's some cheap ones that are good and expensive ones that are bad)

this is the logic of someone who is bad at math. First, it probably makes more sense to only buy level 1 runes (the percentage increase between level 1 and 2 is small and the price jump is high) until you're level 20 but you definitely get a huge benefit from them even if someone posts this as negligible. 9 level 1 malice marks probably adds about 5000 damage per game for Ashe. 9 x 6.25 mana in the blue is at least one more volley every time you leave base. 6 level 1 dodge seals cost about 360 IP (you'll only have 6 before level 20) and for that price one attack in every 30 will miss you. For 20 levels. You could simply buy 6 armors(cost 90 IP) and have about 4.7 more armor vs EVERY attack for 20 levels. This is probably somewhere in the neighborhood of 100k+ total damage prevented for 90 IP in the roughly 100-120 games you have to play to reach level 20. That will earn you an occasional win and more than pay for itself because wins yield more IP and if it even saves your life 2-3 times in the course of all those games it was worth it. No one likes to sit out in the dead pool.

Here's what I go buy:

All credits go to the creator of this Ashe's guide:
http://www.leagueoflegends.com/board...t=81778&page=4

Do not listen to Psychlops. Mana regen/lvl has given me far more success with Ashe and I'm loving it. You can spam volley so much more it's amazing.

I use 18x mana reg/level. armor pen reds and armor pen quints/ms quints/flat hp quints depending how I'm feeling and if I'm soloing or not.

oh and Psychlops is bad.

Don't waste rune slots with mana regen. Ashe doesn't consume massive amounts of mana as she is mainly an auto attack physical DPS. Spamming volley is a bad use of your mana pool as your physical DPS should be out-gaining your volley by far. In addition, your volley doesn't proc on hit effects of your items.

If you absolutely need mana regen, buy a Meki's as your first item.