Several of the Alpha Strike boxes are still available on many places online. I even linked to one on Amazon being sold for less than its original retail price. Although, I actually meant to link to this one, which is only $12: https://www.amazon.com/Catalyst-Game-Labs-35715CAT-BattleTech/dp/B00SYI25WG/ref=pd_bxgy_21_3?_encoding=UTF8&pd_rd_i=B00SYI25WG&pd_rd_r=W6QXBFHQ35WADW23PDV7&pd_rd_w=B43AK&pd_rd_wg=8pNaT&psc=1&refRID=W6QXBFHQ35WADW23PDV7

EDIT: And this one is in stock and sold by Amazon itself: https://www.amazon.com/BattleTech-Assault-Lance-Board-Game/dp/B00QY3BZRO/ref=pd_bxgy_21_2?_encoding=UTF8&pd_rd_i=B00QY3BZRO&pd_rd_r=1TPYRZDQ5CF3DXHATCM1&pd_rd_w=NKMZ1&pd_rd_wg=cRO1M&psc=1&refRID=1TPYRZDQ5CF3DXHATCM1

EDIT2: And most the packs are still available from Catalyst themselves: https://store.catalystgamelabs.com/pages/search-results?q=lance%20pack