For weather you can google averages in those areas but the gear list below should cover all conditions one might experience. For prices and material choices google or visit shops in our home country or where ever you are, second hand used good condition items can be very cheap also. You don’t need to buy very expensive items but quality does generally cost more, lighter and last longer. It will depend on whether this is the one and only trek or you want to keep doing for the next 10-20yrs and quality expensive gear will last longer.
Trekking gear list based on 7 Nepal treks and others over the years with expected 8-10kg pack weight.
Clothes-
Layered clothing to add or remove according to temperature.
Rain/wind proof jacket long length generous fit (treated nylon, pertex or similar, gortex etc)
Down feather or fibre fill puffy jacket (winter conditions November - March)
Fleece top (heavy to medium fleece outside winter conditions)
2 long thin tops (shirt or thermal)
3 T-shirts (trekking in warm weather and base layer)
1 long trekking pants, 1 long thermal bottom or similar pants
1 shorts for trekking in warm conditions
3 under pants, 3 socks, handkerchief
Scarf for winter trek (optional)
Light hand gloves, sun hat, warm head cap
Shoes waterproof ankle or low with good sole grip
Light sandals (optional)
Poncho if rain expected or umbrella medium size collapsible (optional)
Complete list on what else to take:
https://www.lonelyplanet.com/thorntree/forums/asia-indian-subcontinent/nepal/trekking-gear-list
Perhaps do more reading on gear and come back with your own choices for us to comment further as the options are too many to describe.