Price rating approach
Using a string column is not a very ideal solution. How would you for example query for rows where the price range is within or below 70.00$? 

What if you want to do calculations in the database based on the values?

Instead you should use two columns:

create_table "prices", force: :cascade do |t|
  t.decimal   "price_min"
  t.decimal   "price_max"
  t.integer  "percentile"
  t.datetime "created_at",  null: false
  t.datetime "updated_at",  null: false
end


Note that when dealing with money you should use an integer in the lowest unit of currency (cents) or a decimal. See: why not use Double or Float to represent currency?

You can even write a methods in your model to get/set price_range with a range:

class Price
  def price_range
    (price_min..price_max)
  end 

  def price_range=(range)
    self[:price_min], self[:price_max] = range.begin, range.end
  end
end


If you are using Postgres you can use the native range database type. 

create_table :events do |t|
  t.numrange :price_range
  t.integer  "percentile"
  t.datetime "created_at",  null: false
  t.datetime "updated_at",  null: false
end


You can write a helper method to format it nicely

module PriceHelper
  def price_range_human( range )
    "$%s to $%s" % [range.begin, range.end].map(:number_to_currency)
  end
end


See ActionView::Helpers::NumberHelper