The curse of internet tile shopping. I'm having a bad day but hope this doesn't come across as a rant but bear with me. All this talk of quality is ******** and the price means jack all! Just depends on what deal the supplier can get from the factory and how much markup they want to put on it. It is not a true reflection.
Regarding Travertine, regardless of grade or quality, its gonna have holes in it. End of. Its that simple. If it didn't have holes, it would just be Limestone and if you don't want holes, buy a porcelain lookalike or a solid stone.
I work for an independent online retailer, but my advise is DO NOT BUY ANY NATURAL STONE ONLINE (if my boss sees this I'm up for yet another written warning for speaking my mind, but who cares. Job sucks! can't help bring honest). Trav, Limestone, Marble, Slate, Quartz, Terracotta..... Whether you get a sample or not. The images on the website are rarely representative as they are not updated when a new delivery comes in, and natural variations can alter the appearance. A sample is useless as it only shows a tiny variation of a massive batch, and with stock turn around, you can't guarantee your order will even come from that batch.
"Little to no filler", relates to how much is present on the face. Whats visible. That's not to say there are zero holes on the back. Its misleading. Anyone who say "travertine with no holes" is a complete and utter lying bull...... spreader. Premium just means there are less of 'em than others that were cut from the slab, but what was the quality of the slab? whats the quality of the next slab? When they are cut they are normally graded for colour (dark, light or medium). Then "holiness" sorted/catagorised into maybe 4 grades. Premium, standard, commercial and "skip-the-bugger".
If you want a better quality of Travertine don't buy online. Do you homework and not from behind a keyboard and monitor. Get out your chair, get in your car and shop around. Go to several tile or stone shops and physically look at what you are getting. Ask to see a crate of it so you can look through and see the variation and quality. Ask questions until you know everything about it, like what to expect, how to install it, how to seal it, how to repair it when the day comes that it caves in. If you like it, reserve it. Negotiate the price because trust me, there is wiggle room. Do your research before you hand over the cash. Don't buy first and complain about your disappointment of it not being what you expected. Send it back and start a fresh.