I am working on a high dexterity rogue/Archane Archer build. He is currently wearing +8 robes with max. dex. bonus 8, but his adjusted dexterity is 30 giving him a +10 dex bonus.

Is there any armor available that gives greater than 8 dex bonus...

TIA

Javan

Shadow Silk armour (can be purchased on L13) is probably my high dexterity favourite.

Armour of the Turmish (a little trickier to pick up) is also fairly decent.

There is a range of robes/armours which don't limit dexterity. As the topic has been raised before I don't think there are any spoilers here.

Dace De'briago already pointed out two of them and, as he says, the favourite is probably Shadowsilk. Two other possibilites that can turn out better depending on character build and how other equipment stacks are the Drow Blue Mage and Grytelsa's Robes. There is always a downside and the one here is that you have to survive on levels 12 and 13 to get any of them.

Closer to the start line, if you haven't already done so, try the Temple of Oghma.

My favourite for certain levels is still Phaerun's light version of his armour, the no dex limit one. I have been known to switch between that and the armour of the Turmish though...

Any monk robes would also fit the bill. Read in the base descriptions, and it will say max dex bonus 0. As has been discussed elsewhere, the penalty applies to ac, and other dex based skills, but not to attack bonuses, if you are using weapon finesse.