Extira is a good product and is available at Menard's. Menard's only stocks 3/4" material while the 5/4" thickness is a special order. The only downside is that it is sheet goods so you'll have to cut your own boards.
and that is why i love my track saw. my supplier, robert bury in brampton [outside of toronto] stocks all thicknesses. most are available in 4' x 8' or 2' x 16' sizes.
