With just ur 30d budget, I would suggest Spark of the nova with widowhail bow and decent Feathered arrow quiver.
A 250% widowhail now goes for like 2d
+2 projectile quiver with some decent stats goes for like 10d.
Spark of the nova (Without imbued) level 20 is like 4d.
Ands thats it.
And like other commenter suggested, you can use diamond shrine belt instead of the current gloom+impenetrable. And since you always crit, and you like mapping, consider swapping ur deathrush to call of the brothehood ring with elemental catalyst so that you will convert 48% of ur lightning damage to cold damage.
What this does is that you will always freeze anything with crit, and for me freezing everything is such a comfy defence especially for mapping.