You can purchase a portable room air conditioning unit. Some of the ones that go on the window are cheap. Around $100.
If you only have 1 bp then you might just have a marble slab under the cool end. Run cold water on the marble slab or put it in the fridge for a few minutes. The marble stays cool a long time, but you will have to cool the slab a few times during the day. It's not really going to give you stable temps. The portable air conditioning unit would be a better option.
Hope this helps.