How much a TESOL (Teaching English to Speakers of Other Languages) course costs depends on:
A short introductory TESOL course costs around $150-$250 online or $350-$450 in a classroom. This will train you in the basics of TESOL and is suitable if you’re planning on short-term, volunteer TESOL teaching.
To get reasonable, paid work in TESOL you’ll normally need an accredited TESOL (or TEFL course that lasts for a minimum of 120 hours. A good quality, online, accredited 120 hour TESOL course costs in the region of $500. Add on around $50 each for any additional specialist TESOL modules.
A classroom-based 120 hour TESOL course will cost from around $1,500. Fees rise by about 30% if you opt for a major city, can be almost double if you go for a central New York venue and higher still if you choose to go for the CELTA brand.
A combined TESOL course costs around $800-$1,000. This will give you 2-3 days of classroom-based TESOL training on top of an accredited 120 hour online TESOL course.