All marketplaces have lots of LSD listings. I prefer Agora, although at peak times it takes a while to load the site. Ten strips totally vary in price due to the potency of the tabs being sold. But if you’re going for a moderately-dosed tab (~125-150ug), then I wouldn’t pay more than $90-100. And using Tor is fine. I would not want to use the darknet marketplaces in public, considering you’re purchasing illegal substances. 

Tumbling your bitcoins would be the safest way, but a direction transfer is fine. Just know that the bitcoins can be traced back to your Coinbase account if someone really wanted to do it. But I doubt anyone would waste their energy doing so, unless you’re a big-time vendor.