Display add to cart form / +product from node template
Since views seem to be the easiest way to display product offerings, the way I solved this was to create views for the products. The views are configured as blocks. Then I use:

$block = module_invoke('views', 'block_view', $block_name);
print render($block['content']);


to display the block.

I used content type fields to specify the block names I want to display within certain areas so it isn't hard-coded. It isn't terribly elegant, but sometimes programming is that way since there isn't an infinite amount of time to solve problems!