I think given that price range and that power level, you should be looking used. Buying local lets you see/hear it first, avoid the cost of shipping, and reduce your carbon footprint

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A super quick search on Ebay's completed auctions $2-300, I see Fender Rumbles, a Carvin 2x10, Hartke, Ampeg... some good names.
For new amps it's Behringer, which isn't really a popular name, or amps in the 75W range. So that's why I suggest buying used.
Why is 100W your criterion?
How're you gonna use it?
I think your budget is reasonable if you want a great garage/practice space type amp.