they both make T-shirt type looser garments as well as close to skin. id recommend everyone treat themselves to a nice new, close to skin long underwear top from either smartwool or Ibex. I personally think Smartwool longjohn tops are pretty durable, they don't make any cycling specific tops. for SS jerseys, and winter Knickers, Ibex is great! and good softshells as well....
for itchless performance at the thrift stores, look for the "%100 merino" labels. trust me on this one.