I think the fact we have paid for Koeman and Walsh and that they have both cited the investment available, scale of ambition as big reasons for coming we should all relax on the question of availability of funds.
The issue is, as someone else noted, that Martinez left us in a mess. Everyone has money and we are in the third tier (not CL, not Europa League) for most players and agents so we are having to work bloody hard to convince players who have CL/EL alternatives that we are the right choice.
Convincing Koeman & Walsh helps. Good press for Moshiri helps. Talk of a stadium helps. Money helps. However, unless and until one 'name' player takes the plunge the reluctance to commit to us will be there, particularly with Lukaku and Stones still constantly linked with moves.
Blaming Witsel for his obvious lack of desire to come is silly. If you have an offer from Coca-Cola for £50k and great career prospects or an offer from Panda Cola for £60k and uncertain prospects many people would choose the CC offer.