Websites that sell nicotine base (like Nude Nicotine, Heartland Vapes, Nicotine Giant, Liquid Nicotine Wholesalers, etc.) have it in a variety of VG/PG ratios, nicotine mg options, and in a variety of sizes.
If you vape 70VG/30PG and 3mg flavorless, for example...just choose those options and the size bottle you want. You'll most likely get a better price for it, too, than buying 100mL (or other small quantities) from websites that sell mainly finished, flavored, eliquids.