②→ There are various apps and websites that will help you sell your __ items.
unwanted
unwarranted
unexpectedly 

③→ If you have something that’s worth $1,000 or more, you might consider getting an __.

appraise
appraisal
apparatus 

④→ Some online shops are free and with no __ fees.
transaction
transparent 
transportation

⑤→ 名古屋伏見英会話スクール ロケイシャス (LoQuacious) will soon have an online English app for a __ price.
reason
reasons
reasonable