There are several options.
1. Spacers. these lift your bars up. common is 1/2" and 3/4". some even have two sets of holes so you can change the angle a bit. $50
2. Helibars. Nice bit of kit that allows you to adjust the radial angle of the bars relative to the forks, and height also. $300+
3. Cycle Cat bars. Lovely machined bits of aluminum. Huge range of angles and positions. Not in production any more, as the company folded several years ago. $350
4. Spiegler / LSL Kit comes with a new top triple clamp and aluminum bars. Higher and further back. Had them on my 98 for years and loved them. Now on my brother's bike. $350
5. Get a top triple clamp from a Monster S4. It fits the ST (same chassis) and uses standard bars. Price dependent on your e-bay skills.
Its questionable whether any of the above options are still in production.
I am still appalled that Ducati introduced the ST with basically fixed bars, especially when they had the Monsters's top triple clamp available. Put regular handlebars on it so we can make changes to fit our body size, and riding style. But that's an old rant.
I went through this same issue w/ my 99 ST4. It came w/ the Spengler top clamp and superbike bars installed when I bought it. The resulting riding position was uncomfortable for me, so I first added a 30 mm spacer to raise the bars. That helped a bit, but the bar position was still too far forward for me, causing a lot of wrist pain.
At the moment, I have a set of BMW-type bars on the bike, along w/ the spacers, using the Spengler top clamp. This mod required new brake lines and splicing in an additional wiring section on the right side switch. This made the riding position much more comfortable for me. I will probably remove the spacers soon, since I don't think I need the bars quite so high as they are now.
Once you have the Spengler or S4 top clamp, you can use standard bars, which opens up a lot of options for you. But you may need to add longer brake and clutch lines and even some additional wiring length if you deviate too far from stock. But if you are as uncomfortable as I was in the stock or near-stock position, it's worthwhile, IMO.