If youre looking at skinsuits from an aero advantage then velotec is your best choice in the budget, unless you can find a BioRacer in a sale or on ebay.
I only have skinsuits the best tbh are Pedal Ed from sizing comfort and fit point of view and the mesh front on their aero suit is excellent in the velodrome or summer. Rapha are incredibly good but insanely expensive (although their custom aero suits are pretty cool)
Velotec give the best aero advantage but dont last I have two or three and they didnt last one track league season. the zips gave up quite quickly and the legs seem to get loose wish constant washing.