Not at fault car is deemed a total loss, need help got lowballed
I was in a collision about a week ago and insurance just got back to me saying the car is a write off. They offered me $1000... They said they appraised it for $3000 and from there $500 deducted because its "rebuilt" (is this a thing) and $1500 for "high mileage". I will admit It has high mileage but that's on a new transmission with engine work done which is why it went to 400k km, it would have easily gotten over 600k and i was planning on riding it out till it died because its reliability was too hard to give up (I am a student). Also my vehicle was in excellent condition, brake lines done in April and new window regulator two weeks ago.
What are my options, online I can find the same vehicle that range from $5000-$3000, i just cant match the mileage. Also is the $500 for rebuilt a legit value they use when doing appraisals?