I originally wanted a Lucida (until we went to try them on again in person and I decided on the Tiffany & Co Classic solitaire instead (it sparkles so much more) but all the info we got was on the Lucida) so we went to try them on a few weeks ago. A 1ct H VS2 was about $12,000. The Lucidas are also more expensive than the classic solitaire which would be about 10k with the same C's. My best guess is that the .75 ct with the worst color and clarity would be around 8-9k. I would be sure to have your friend go look at the rings in person before giving her bf the final decision. I was set on the Lucida for 2 years because the setting is really pretty but the sparkle and shine of the solitaire in comparason made me change my mind. Now that the round Tiffany solitaire is on my finger, I dont regret my change-of-opinion at all! =) Best luck to your friend in getting her dream ring!
PS - I think the Tiffany phone reps inflate the price to cover their butts for some reason. When we called asking about a specific carat size's price, they gave us a really high number. When we then went into the store a couple of days later, the sales associate reading off the computer specific diamonds gave us a much more reasonable cost.