Sorry Izzy. Not without a few drinks and some dancing...
This type of request is not uncommon.
The reason this happens is because everything is considered a number to the AI. And a partially researched tech is only considered a smaller fraction of the whole tech in value. In the AIs mind, a tech which they have 80% researched is only worth 20% of the total value to them. Therefore this is a legitimate trade.
The next reason is because the AI is programmed to request trades with the played only every so many turns. This is to prevent the AI from bugging you every turn. This is also why, with many active AIs, you get tons of requests all at the same time.
In the screenshot Lemon Merchant posted, it just so happened that the "lets make a deal" showed up when Isabella was nearly done with Currency, so its value was extremely low for Isabella. In fact, you can see that she is 2 turns away from finishing it!
To use this information to your advantage, the AI "knows" how far away you are from finishing a tech, and adjusts their trades accordingly. If the AI won't give up a high beaker technology for a reasonable price, try putting a few turns of research into it. You might not be able to save 25 turns of research, but perhaps you can save 21 turns.
Edit: May as well add a funny picture if I'm going to post here.
Waaaait, whose farm and pasture?