This is a console app or is that just for your example? If a console app, I would start by displaying a list of the choices they have to pick from with an item/row number starting each line and then asking for them to type that item/row number in for the input. Also remember what is read/written is already text even if there writing a number...
Dim strEngineChoice As String = ""
Console.WriteLine("Enter 1 for six cylinder")
Console.WriteLine("Enter 2 for eight cylinder")
Console.WriteLine("Enter 3 for disel")
strEngineChoice = Console.ReadLine
Select Case strEngineChoice
Case "1"
Console.WriteLine("Price : $150")
Case "2"
Console.WriteLine("Price : $475")
Case "3"
Console.WriteLine("Price : $750")
Case Else
Console.WriteLine("Invalid selection")
End Select