JBL makes a good and low cost outdorr model, for under $200 with all mounting hardware.....I wouldnt overthink an outdoor unit......I had a pair of the JBL and they sounded great, but everything sounds good in the outdoors with friends.
Outdoor Speaker Recommendations
Setting up two outdoor zones - 2 speakers in each. They will be driven (initially) by a Onkyo TX-SR674. In about 1 month they will be driven by the Pioneer Elite VSX-82TXS. As you can tell I'm not a high-end guy but do spend reasonably on speakers - have some Klipsch IIIs and Paradigm speakers.