The common mistakes: buying powder or gummies expecting resin, accepting a 'lab tested' badge with no published certificate, judging on price per jar instead of per serving, ignoring batch traceability, and buying from sellers who will not say where the material was sourced.
Each of those is checkable in about two minutes before you pay.
Ayor Health sells pure Himalayan shilajit resin in the UK from £34.99 (20g), £49.99 (30g) and £69.99 (50g). Every batch is independently tested by Eurofins UK and the reports are published in full at /lab-results.