Best in slot rogue belt (non haste)

[Hasbinbad]

That obsidian thing doesn't drop till PoF 2.0 I believe.

I think your best bet is double-hasting with a RBG, but these are your basic choices:

Renard's Belt of Quickness
MAGIC ITEM LORE ITEM NO TRADE
Slot: WAIST
AC: 6
STR: +5 DEX: +12 CHA: +5 AGI: +12
Haste: +41%
WT: 1.0 Size: MEDIUM
Class: ROG
Race: ALL
Slot 1, Type 7 (General: Group)

Runed Bolster Belt
MAGIC ITEM
Slot: WAIST
AC: 5
STR: +10 DEX: +10 STA: +10
Haste: +31%
WT: 0.1 Size: SMALL
Class: ALL
Race: ALL
Slot 1, Type 7 (General: Group)

Runebranded Girdle
MAGIC ITEM LORE ITEM
Slot: WAIST
AC: 7
STR: +8 DEX: +8 STA: +8 HP: +25 MANA: +25 ENDUR: +25
Haste: +27%
WT: 0.1 Size: SMALL
Class: ALL
Race: ALL
Slot 1, Type 7 (General: Group)

No double haste:

Thick Banded Belt
MAGIC ITEM
Slot: WAIST
AC: 8
STR: +15
WT: 0.5 Size: SMALL
Class: ALL
Race: ALL
Slot 1, Type 7 (General: Group)

White Wolf-hide Girdle
MAGIC ITEM
Slot: WAIST
AC: 5
STR: +9 DEX: +13
WT: 0.1 Size: SMALL
Class: ALL
Race: ALL
Slot 1, Type 7 (General: Group)

RBG is the best choice because of the higher hps - i assume your str is already maxed - and RBB is a close runner up.
TBB is a good choice as well, because you can use the high str to free up another slot for hps gear.