Most Odoo quotes in Bangladesh look cheap because the expensive parts are missing: data migration, UAT, hypercare, Mushak output. Tick what your proposal actually includes to see the gaps, what they typically cost later, and the exact questions to send the vendor.
How to read this. The price range is the implementation-fee band used by the cost estimator for your size, adjusted for industry. It excludes the Odoo licence. "Typical cost if added later" is what these items usually cost as change requests from Bangladeshi partners. That's why a quote missing them is cheaper only on paper. Nothing you enter leaves your browser.