It's well established fact that a club like Nottingham Forest cannot compete with Manchester United, or the rest of the Premier League's top six, in the transfer market.
The Reds have a massive pull but financially they cannot match the richest teams in the country, which is the same story for the majority of the top flight. But just because you have more money does not mean you necessarily spend it more wisely.
Indeed, this has been the problem for Man United in particular in the post-Sir Alex Ferguson era. Hundreds of millions of pounds have been spent on transfer fees, wages and agents fees with very little to show for it.