Tombow is my favorite too! I also like the 2-way glue pen (scrapbooking) and sticky strip for the extra hold times.
I did get a good price of $1.88 each for the refills through Viking, FREE shipping on $25 AND $20 off a $50 purchase. Unfortunately, they merged with Office Depot and the prices and coupons are no longer that good! If you want to purchase a large amount, I have been told to call Office Depot and speak to someone about the best price. You can also search internet sites for lowest prices.
I, too, stocked up when they were $1.88 with the $20 off the order so I am still set.