Is $300,000 to push back and heighten a retaining wall with soldier piles a fair price?

My 6-foot by 50-foot retaining wall in the backyard is starting to spall and deteriorate. My home inspector said I likely have a few more years before serious issues arise, as there's no leaning yet. I'm trying to understand my options for this slope, ideally I'd like to remove the wall entirely, but I understand that's impossible. I'm looking for ideas on what I can do with this wall and how to properly proceed, and if a $300,000 quote is even reasonable. I'm open to other solutions besides one giant wall, as the current wall is eating up a large amount of space and it would be nice to reclaim or make it functional. The wall is 6 feet tall and 50 inches wide, retaining about 20 feet of soil on a gradual slope, and is adjacent to four different residential lots.