Generic Roundup? Listed as glyphosate on the ingredient label.

The beauty of glyphosate is it will pretty much kill everything. Other herbicides tend to be more selective or have long residuals which create larger limits on use.

Every glyphosate product I have seen is priced in the same range, very expensive. What to use will depend on what you need to remove but most often the old fashioned way of digging the plant out is the best, and least expensive, way to get rid of it.
Shrubs, very often will need to be dug out after they are killed by an herbicide anyway. Dpending on where the "weeds" are they may also need to be dug out after being killed since the dead plant tissue will serve as a food source for future plant growth.