you can find a lot of that stuff on craigslist.
for Mats, try www.getrung.com
for heavy bags, www.everlast.com
they also make thai pads, focus mitts, etc.
i also like fairtex, but they can be expensive.
you can also visit the store on my website for some good deals. www.dansmuaythaimma.com
Best wishes. Post some photos when you are done.