Danetta's Oath consists of two 1h crossbows, at around 400 dps+ each, which can be aquired for about 500k or so for both, with decent stats.
Is it worth buying? I can afford it and then some, and if I bought them I would use this build.
I currently have a weapon with 830 dps, 39% damage, and a quiver with over 100 dex and some decent stats.
If you're totally set on dual xbows, it's worth it as those are the best you could get, but overall 2-handers are going to give you more damage in the end - bows in particular.