I am slowly getting back to cycling, after having had a neck injury (not bike related). When I injured myself, I had a brand new Myka sport which was left unused for two years.

I started out terrified and adamant at wanting a bike that let me put the feet on the ground from the saddle. Given that I am 5' tall, it was virtually impossible, even with the bikes designed for that purpose. Yesterday I tried a Specialized Expedition and I couldn't even reach with the tips of my toes. But even if I give up the idea of having a bike with this feature, I liked from the expedition two things: the super low step (which alleviates my fears of having to dismount to stop) and the more upright position (great for my neck) and the saddle.

I asked the salesman about the possibility of just changing stuff (mainly the stem or the handlebars) to my existing bike, rather than spending $500 in a new one. He made it sound like an impossible feat, not worth the effort. (He pointed at the shifters and breaks, and said "you'd have to change all that"). I am not sure whether he was realizing he was going to lose a sale or what.

So realistically, how hard and expensive is it to change a stem or a handlebar? Would a more upright position work with a mountain bike geometry? Does changing a stem change too much the handling of the bike? (I tend to suffer from "wobbliness" sometimes and some bikes are more wobbly than others). What kinds of stems should I consider?

Thanks

Diana