Your biggest upgrade would be to get a amulet with avarage dmg, dex, high crit chance and high crit dmg. That alone would give you a 15-20k dps boost at least. Next get inna's belt. It would be a huge upgrade for your budget (you can't get any decent witching hours for that money). Those 2 pieces would be the best upgrades that you can get right now. If you have any gold left, get some gloves with high dex, crit chance anc crit dmg. Also, you might want to save some gold in the future to put the best green gems you can afford in your manti.