train costs to Paris

You'll find at least some of that answer on the German Rail website.

You can do it on Thalys in about 2½ hrs (Aachen) for €98, standard fare, or as low as €29 for an advance purchase "Smoove" fare.

I agree with Lee. The German Rail site is your best site for detailed timetables for virtually all of Europe. For Aachen-Paris you can get the same €29 Smoove fare at www.thalys.com. Whether you book on the DB site or the Thalys site, the key is to book ASAP (up to 92 days in advance). The allotted number of Smoove fare tickets sell out quickly.

If you book Maastricht-Paris well in advance on the NS Hispeed site, you can get a discount fare of €48 which includes a ticket on an IC train from Maastricht to Liege-Guillemins and a ticket on a Thalys train from there to Paris.

It's a little more complicated to get a discount fare ticket for Luxembourg-Paris. A Prem's ticket can cost as little as €25 and you can print the ticket yourself. Book at www.voyages-sncf.com. If you can't handle the French, use the Google Toolbar to translate the site into English. Do not choose to have the ticket mailed to you because you do not live in France. Again, book ASAP (up to three months in advance).

Thanks for the info on the train sites and how to get the 'smoove' rate.
I went to site for 'thalys' and got a r/t tkt for 68euro from Aachen to Paris.
This was a great site.