I am a total webcomic addict.
The world totally needs more webcomics, and since you've already got a willing artist, I say go for it! There's tons of free comic hosting sites online (drunk duck, keenspace, etc), so aside from investing your time and energy, its all benefits with no costs (just not financial benefits, most likely). You shouldn't expect to make money off of a webcomic, but still, there's enough good points to make it worthwhile if you have the time. The biggest one I think is being the fanbase--especially when you've got other stuff that
is in print, that you can point your fans to.
And there are ways to motivate people to buy a TPB version of your webcomic. The best way I can think of (or at least, the kind that, as a comic purchaser, I always like the best) is extra content--extra comic material that you can't get online. In Ursula Vernon's
Digger, this takes the form of several pages of extra (and entertaining) background; In the comic
9th Elsewhere, its in the form of extended conversations within the chapters. Some people really like to have the book versions of comics, so a little bit of incentive can be enough to get rid of their money-spending guilt over buying something that is already free.
Some comics, especially in long running ones where the early art isn't the same quality as the more recent art, go as far as to redo sections of the comic;
Inverloch redid the prologue, and
Earthsong reded the whole dang first and second volumes. But, that's the kinda time consuming I wouldn't get into unless it's
really necessary; and if your art is good in the first place, I wouldn't waste the time when you can be drawing
new stuff.
Aside from selling copies of the book, some
really successful webcomics do make money in other ways.
Dominic Deegan has wallpapers offered every month that you can get for a $1 donation. He also sells posters and t-shirts. the most amazing thing, though, was when he did a donation drive, promising to do twice as much comic every week if he could get...I think it was about $12,000 in donations in a couple of months. And it totally worked. o.o The comic
Alien Dice does a similar thing, where it promises extra updates if they meet a monthly donation quota. So for some people, the begging+bribing combo works well. XD
Those are exceptions to the rules though; but still, can't hurt and you may make a little extra hand cash. Maybe.