amp makes less difference then speakers in 99 out of 100 cases. modern amps are mostly all fairly clean. going from a 100$ amp to a 300$ amp is not going to be very noticeable in most cases. however, going from 100$ - 200$ speakers is very noticeable, let alone spending more. i would not spend above 200$ on an amp unless you plan on spending a chunk more. you will end up micro upgrading and sidegrading and spending a lot of money doing it.
i would skip the topping and go even cheaper chifi brand like FX or Nobosound. you wont notice a difference and will save you 50+$ to spend on speakers or beer or a steak dinner.
edit: unless your willing to go used. used 300$ market can net you some very great amps.