Let's start with limited things....new limited tokens and metallex versions of them are now listed
In addition to that Boros is historically speaking a weak colour pair in Sealed as it lacks lategame and without clear, strong synergies to make up for the missing top-end, I would caution against going for Boros at your Pre-Release
If you buy a 5,000-card lot for $50 and pick 200 above-bulk cards worth listing individually on eBay, those 200 cards might generate $300 to $500 in sales
Staples from these sets include Night Stretcher, the ACE SPEC cards, Latias ex, and Pikachu ex in Surging Sparks and Dragapult, Munkidori, Bloodmoon Ursaluna and Ogerpon in Twilight Masquerade
Because SAR supply is finite and moves continuously, checking the card list pages for current availability is the most reliable way to catch specific cards when they come in stock