On a budget, I would guess this combo might work OK. Personally, I wouldn't bet my safety/life on it though. About half my riding (which equals about 25 miles per week) is in the dark. Increased exposure = increased risk, so I personally wouldn't take my chances with this setup. Consider the cost of good lights part of the cost of cycling. For me, if I couldn't afford decent lights, I wouldn't ride in the dark.

My light set-up: MS900 ($90) + DiNotte 140L ($89) (I bought the Eneloop battery pack w/charger at Costco on sale for $20 which powers the DiNotte). You could get an excellent setup for both night and day time riding for less than $200.

Geoman said here on another forums that the tail light will be available on 05-21-10. No word on specs or cost yet. However, the DiNotte 140L is a 3w LED which is the same as the new MS tail light. Given MS's pricing history, it'll likely be significantly less than the DiNotte 140L with speculatively about the same output.

I also just noticed Geoman is selling the MS900 plus (the one with the waterproof MS1400 battery) for $89.99.

A word on visibility: visibility is more than lighting. I also use a decent reflective vest (I've learned over time and with experience the $5 Harbor Freight vest is the best value/performance vest available) and have adequate reflectors.

How much is your life and/or health worth?