\def with \expandafter help:

\expandafter\def\expandafter\MySaved\expandafter{\MySaved \MyText}


If you are using LaTeX (\textbf, \textit, ...), then
\g@addto@macro can be used:

\makeatletter
\g@addto@macro\MySaved{\MyText}
\makeatother


Or if you need complete expansion:

\edef\MySaved{\MySaved \MyText}


But that might break fragile stuff, thus LaTeX provides \protected@edef:

\makeatletter
\protected@edef\MySaved{\MySaved \MyText}
\makeatother


Or if \Mysaved and \MyText should be expanded once exactly, e-TeX's \unexpanded helps:

\edef\MySaved{%
  \unexpanded\expandafter{\MySaved}%
  \unexpanded\expandafter{\MyText}%
}


The same can be achieved by token registers in vanilla TeX:

\toks0\expandafter{\MySaved}
\toks2\expandafter{\MyText}
\edef\MySaved{\the\toks0 \the\toks2}


Is there an "Appending \let"?
I need to display custom price for each product where the admin will set different price for each product. and this product price only should be displayed in product listing and product view page, without changing the product actual price. And also the same price should apply to the cart. I tried with catalog_product_get_final_price observer, but It shows the price as special price but it will not change the display of product price. Please give me an idea, how can I do this? Thanks in advance:)
