The most economical way to transform your jacket would be to cover the lapels with a synthetic fabric with a silk look/finish to it. Starting just above the top button. If you remove the current lapel facing and apply this cloth the price will increase significantly. If this is done, make sure the tailor knows to put domet cloth under the facing. If you use silk that is meant to be used for tux facing, double or triple Manton's estimate. Whatever you do, start above the buttonhole, so you don't need to remake the buttonholes.
The braid for the trouser has its own issues. Front pocket style is one of them. The braid will need to be set into the waistband, the full length of the inseam opened and resewn and rehemming. Applying the braid will be a combination of machine & hand work or could be completely done by hand at a higher cost I'm sure.
Depending on your needs, a great tux is a good investment. If it is black tie, it is a special social or business event. If business you are amongst your peers and want to look your best and remain professional. No short cuts.