The Pilot 78G is generally considered to be one of the better fountain pens in the "budget" category. Although I may be mistaken, the 78G may technically be discontinued or otherwise unavailable in the United States. Even if that is true, there is an abundance of overstock on the market, and it's pretty easy and financially painless to acquire a 78G.
I got the teal colored pen, with a medium sized nib. It came with a black ink cartridge (one that only fits Pilot pens), a
CON-20 squeeze-type ink converter [edit: that is similar to a CON-20 converter], and an extra large bag of awesome. Is the nib as smooth and consistent as, say, my Pelikan M205 or my Pilot Custom Heritage 91? No. Is the pen body cheap, lightweight, and plasticky? Yup. Is the faux gold trim cheesy and tacky looking? I think so. So what? The 78G costs less than a couple of Happy Meals at McDonald's. At that price point you could almost treat it as a disposable pen!
The pen writes well enough, doesn't skip, and isn't too scratchy. It comes in different colors and different nib sizes. It is cheap enough to buy on a whim, and you won't lose any sleep if your kid happens to bend the nib, use it as a dart, or trade it for a not-so-rare Pokemon card.
I was going to describe the pen in more detail, but then I found a much better review with great pictures, all of the specs, and even a video. I hope the folks at Gourmet Pens don't mind the reference:
Pilot 78G Review. Oh, and here's another good review at Ink of Me Fondly:
Another Pilot 78G Review. The pen in the first linked review has a broad nib, and the pen in the second linked review has a fine nib, in contrast to my medium nib.
The above picture shows the 78G in a disassembled state, with the ink cartridge installed. No surprises there. I'll finish this post with some writing samples on different types of paper.
The first sample also includes short blurbs written with other fountain pens that are described
elsewhere on this blog, just for the sake of comparison.
The bottom line with me and the 78G: it's well worth the price and is a decent pen, but I'd rather use my Pilot Custom Heritage 91. In fact, I gave the 78G to my son for use as a school pen. I would recommend the 78G as a "first real fountain pen" (rather than, say, a Pilot Varsity, a Platinum Preppy, or a Lamy Safari).