As said before a very general question....
Just to clarify a L2 switch cannot be ''converted'' into a L3 switch. For example, if you have a 2950/2960 which are L2 switches, you cannot magically convert them to work as L3 switches.
On the other hand, if you have let's say a 3560/3750 working as a L2 switch and want to convert it to a L3 switch, you can enable '' ip routing'' and set ''no switchport'' on the physical ports to behave as routed ports.
If you want to purchase L3 switches, then to know the answer, we need to know what do you want to do, etc...
Federico.
