I need advice on archiving projects in a way that would let me do future changes if need be. I don't want to use an external HDD for each project because of cost and reliability, but optical media (DVD) sometimes means as much as 100 disks or more to archive everything.

I thought of not archiving the clips, since I have those on MiniDV tapes anyway, and only backing up one copy of the uncompressed movie (which I can use regardless of the editing suite), the project file and anything that's not on tape (images, sound clips, generated media, etc.). At worst, I might have to re-capture clips from the MiniDV tapes to make changes, but that's such an unlikelihood that it's an acceptable compromise.

Any suggestions?

Blu-Ray disks are getting pretty cheap. You can get them for less than 3 bucks a piece nowadays, and they hold 5 times as much data as a DVD, do the project that takes 100 DVD disks would only take 20 Blu-Ray disks - still a lot of disks, but certainly more manageable.

Cost of storage on hard drives isn't really that expensive. It's comparable to DVD cost, per gig, if you use big drives (and getting cheaper all the time). I don't suggest getting pre-made external drives though. An external device, that you can easily swap drives with, makes a lot more sense for archiving (connect by eSata and it's fast too):

Newegg.com - VANTEC NexStar NST-D100SU Plastic 2.5" or 3.5" USB2.0 & eSATA Hard Drive Dock - External Enclosures (http://www.newegg.com/Product/Product.aspx?Item=N82E16817392022)

Good hard drives are likely as reliable storage as burned optical disks. I think Hitachi is probably making the most reliable mainstream hard drives nowadays. They run nice and cool compared to Seagates, from what I've seen, and customer feedback on Seagates, at Newegg has taken a bit of a dive lately. Seagate has also done away with the 5 year warranties they used to offer. That's got to tell you something.

Another thing you can do that could help, is to use lossless compression for archiving, rather than storing completely uncompressed files. Simply convert back to uncompressed if you should need to edit something you've archived.

This is a good lossless codec for archiving (and it's free):

MSU Lossless Video Codec (http://compression.ru/video/ls-codec/index_en.html)