Want to buy a Libretto or some special parts? Post your most desired Libretto model, harddisk or other Libretto thingy and you might find somebody to sell it to you.
I'd definitely go for it if the machine is in good condition. The Libretto L3s are fantastic little machines. Unfortunately I have no idea what they are worth or what you should pay so I can't help you there. Have you tried searching the web for price comparisons?
In the last month, there have been a few Libretto U100s on sale on Trademe (NZ equalivant of ebay) going for between $500 and $1000 NZD and everytime I have to put my credit card far away from me because it's just so tempting.
I would be tempted to make a collection of all the libretto models when I get a bit more spare $$.