Tobacco is tobacco, and unless it's a godawful, chemical-tasting, humectant soaked, cheap leaf blend, then you could jar it if you don't love it and come back to it months, years later. You could then maybe realize it's the most sublime thing you've ever tasted, be it because it aged well or because your palate and preferences changed. Were that not the case, many people will be more than happy to trade aged tobacco, so there is an argument to be made for taking a risk in buying more quantity and saving money while at it.
That said, I tend to go with 50g tins or 2oz in mason jars if I'm trying a blend. I'll buy 100g+ once I know I like a particular mixture or if it's a genre I love, with the exception of when it's a raved about/hard to get tobacco and the window opens to buy some (I bought some FVF 250g boxes before I tried it).
Good were the days of samplers, the PAX Crawls, the Pipe Tobacco of the Month Club. Those were fantastic for trying blends that might not have been on one's radar. P&C still has samplers, and the Battle of the Blends is a great way to try and pay less for 50g tins. In fact, they had a tin of Orlik Dark Strong Kentucky and one of Mac Baren ODF for $16, I think.
The ideal scenario in the sampling phase is to have pipe smoking friends, or a nearby pipe club. That way you can split the cost, try a wider variety and begin deep cellaring your favorites quicker. Sure, I want to be like JimInks when I grow up, but at the rate I smoke right now I know I'll discover many blends I'll love way past the 2021 mark if I go at it alone. That's why I'm spreading the tobacco gospel among my friends and I started a scraggly pipe club 4 people strong.
In the end, you do you, and keep going with the methodology that works best for you.